[yugabyte#25270] docdb: fix uninitialized isolation level at PgsqlLockOperation::GetDocPaths

Summary:
```
../../src/yb/docdb/conflict_resolution.cc:865:5: runtime error: load of value 4458368, which is not a valid value for type 'IsolationLevel'
[m-1] W1212 08:27:12.423846 99051 master_heartbeat_service.cc:426] Could not get YSQL db catalog versions for heartbeat response:
[m-1] W1212 08:27:12.425787 99052 master_heartbeat_service.cc:426] Could not get YSQL db catalog versions for heartbeat response:
    #0 0x7fd9ae920c0e in yb::docdb::(anonymous namespace)::GetWriteRequestIntents(std::vector<std::unique_ptr<yb::docdb::DocOperation, std::default_delete<yb::docdb::DocOperation>>, std::allocator<std::unique_ptr<yb::docdb::DocOperation, std::default_delete<yb::docdb::DocOperation>>>> const&, yb::dockv::KeyBytes*, yb::StronglyTypedBool<yb::dockv::PartialRangeKeyIntents_Tag>, yb::IsolationLevel) ${YB_SRC_ROOT}/src/yb/docdb/conflict_resolution.cc:865:5
    #1 0x7fd9ae9190ce in yb::docdb::(anonymous namespace)::TransactionConflictResolverContext::GetRequestedIntents(yb::docdb::(anonymous namespace)::ConflictResolver*, yb::dockv::KeyBytes*) ${YB_SRC_ROOT}/src/yb/docdb/conflict_resolution.cc:1130:22
    #2 0x7fd9ae90fcee in yb::docdb::(anonymous namespace)::TransactionConflictResolverContext::ReadConflicts(yb::docdb::(anonymous namespace)::ConflictResolver*) ${YB_SRC_ROOT}/src/yb/docdb/conflict_resolution.cc:1164:22
    #3 0x7fd9ae8fd333 in yb::docdb::(anonymous namespace)::ConflictResolver::Resolve() ${YB_SRC_ROOT}/src/yb/docdb/conflict_resolution.cc:198:26
    #4 0x7fd9ae8fc3b2 in yb::docdb::(anonymous namespace)::WaitOnConflictResolver::TryPreWait() ${YB_SRC_ROOT}/src/yb/docdb/conflict_resolution.cc:697:25
    #5 0x7fd9ae8fc3b2 in yb::docdb::(anonymous namespace)::WaitOnConflictResolver::Run() ${YB_SRC_ROOT}/src/yb/docdb/conflict_resolution.cc:670:7
    #6 0x7fd9ae8fa47d in yb::docdb::ResolveTransactionConflicts(std::vector<std::unique_ptr<yb::docdb::DocOperation, std::default_delete<yb::docdb::DocOperation>>, std::allocator<std::unique_ptr<yb::docdb::DocOperation, std::default_delete<yb::docdb::DocOperation>>>> const&, yb::docdb::ConflictManagementPolicy, yb::docdb::LWKeyValueWriteBatchPB const&, yb::HybridTime, yb::HybridTime, long, unsigned long, long, yb::docdb::DocDB const&, yb::StronglyTypedBool<yb::dockv::PartialRangeKeyIntents_Tag>, yb::TransactionStatusManager*, yb::tablet::TabletMetrics*, yb::docdb::LockBatch*, yb::docdb::WaitQueue*, std::chrono::time_point<yb::CoarseMonoClock, std::chrono::duration<long long, std::ratio<1l, 1000000000l>>>, boost::function<void (yb::Result<yb::HybridTime> const&)>) ${YB_SRC_ROOT}/src/yb/docdb/conflict_resolution.cc:1401:15
    #7 0x7fd9aff22ca9 in yb::tablet::WriteQuery::DoExecute() ${YB_SRC_ROOT}/src/yb/tablet/write_query.cc:801:10
    #8 0x7fd9aff1fda3 in yb::tablet::WriteQuery::Execute(std::unique_ptr<yb::tablet::WriteQuery, std::default_delete<yb::tablet::WriteQuery>>) ${YB_SRC_ROOT}/src/yb/tablet/write_query.cc:618:28
    #9 0x7fd9afb9b708 in yb::tablet::Tablet::AcquireLocksAndPerformDocOperations(std::unique_ptr<yb::tablet::WriteQuery, std::default_delete<yb::tablet::WriteQuery>>) ${YB_SRC_ROOT}/src/yb/tablet/tablet.cc:2147:3
    #10 0x7fd9afd166d7 in yb::tablet::TabletPeer::WriteAsync(std::unique_ptr<yb::tablet::WriteQuery, std::default_delete<yb::tablet::WriteQuery>>) ${YB_SRC_ROOT}/src/yb/tablet/tablet_peer.cc:704:12
    #11 0x7fd9b0fd4d57 in yb::tserver::TabletServiceImpl::PerformWrite(yb::tserver::WriteRequestPB const*, yb::tserver::WriteResponsePB*, yb::rpc::RpcContext*) ${YB_SRC_ROOT}/src/yb/tserver/tablet_service.cc:2325:16
    yugabyte#12 0x7fd9b0fd711a in yb::tserver::TabletServiceImpl::Write(yb::tserver::WriteRequestPB const*, yb::tserver::WriteResponsePB*, yb::rpc::RpcContext) ${YB_SRC_ROOT}/src/yb/tserver/tablet_service.cc:2345:17
    yugabyte#13 0x7fd9a91098ec in yb::tserver::TabletServerServiceIf::InitMethods(scoped_refptr<yb::MetricEntity> const&)::$_0::operator()(std::shared_ptr<yb::rpc::InboundCall>) const::'lambda'(yb::tserver::WriteRequestPB const*, yb::tserver::WriteResponsePB*, yb::rpc::RpcContext)::operator()(yb::tserver::WriteRequestPB const*, yb::tserver::WriteResponsePB*, yb::rpc::RpcContext) const ${BUILD_ROOT}/src/yb/tserver/tserver_service.service.cc:848:9
    yugabyte#14 0x7fd9a91098ec in auto yb::rpc::HandleCall<yb::rpc::RpcCallPBParamsImpl<yb::tserver::WriteRequestPB, yb::tserver::WriteResponsePB>, yb::tserver::TabletServerServiceIf::InitMethods(scoped_refptr<yb::MetricEntity> const&)::$_0::operator()(std::shared_ptr<yb::rpc::InboundCall>) const::'lambda'(yb::tserver::WriteRequestPB const*, yb::tserver::WriteResponsePB*, yb::rpc::RpcContext)>(std::shared_ptr<yb::rpc::InboundCall>, yb::tserver::TabletServerServiceIf::InitMethods(scoped_refptr<yb::MetricEntity> const&)::$_0::operator()(std::shared_ptr<yb::rpc::InboundCall>) const::'lambda'(yb::tserver::WriteRequestPB const*, yb::tserver::WriteResponsePB*, yb::rpc::RpcContext)) ${YB_SRC_ROOT}/src/yb/rpc/local_call.h:126:7
    yugabyte#15 0x7fd9a91098ec in yb::tserver::TabletServerServiceIf::InitMethods(scoped_refptr<yb::MetricEntity> const&)::$_0::operator()(std::shared_ptr<yb::rpc::InboundCall>) const ${BUILD_ROOT}/src/yb/tserver/tserver_service.service.cc:846:7
    yugabyte#16 0x7fd9a91098ec in decltype(std::declval<yb::tserver::TabletServerServiceIf::InitMethods(scoped_refptr<yb::MetricEntity> const&)::$_0&>()(std::declval<std::shared_ptr<yb::rpc::InboundCall>>())) std::__invoke[abi:ue170006]<yb::tserver::TabletServerServiceIf::InitMethods(scoped_refptr<yb::MetricEntity> const&)::$_0&, std::shared_ptr<yb::rpc::InboundCall>>(yb::tserver::TabletServerServiceIf::InitMethods(scoped_refptr<yb::MetricEntity> const&)::$_0&, std::shared_ptr<yb::rpc::InboundCall>&&) ${YB_THIRDPARTY_DIR}/installed/asan/libcxx/include/c++/v1/__type_traits/invoke.h:340:25
    yugabyte#17 0x7fd9a91098ec in void std::__invoke_void_return_wrapper<void, true>::__call[abi:ue170006]<yb::tserver::TabletServerServiceIf::InitMethods(scoped_refptr<yb::MetricEntity> const&)::$_0&, std::shared_ptr<yb::rpc::InboundCall>>(yb::tserver::TabletServerServiceIf::InitMethods(scoped_refptr<yb::MetricEntity> const&)::$_0&, std::shared_ptr<yb::rpc::InboundCall>&&) ${YB_THIRDPARTY_DIR}/installed/asan/libcxx/include/c++/v1/__type_traits/invoke.h:415:5
    yugabyte#18 0x7fd9a91098ec in std::__function::__alloc_func<yb::tserver::TabletServerServiceIf::InitMethods(scoped_refptr<yb::MetricEntity> const&)::$_0, std::allocator<yb::tserver::TabletServerServiceIf::InitMethods(scoped_refptr<yb::MetricEntity> const&)::$_0>, void (std::shared_ptr<yb::rpc::InboundCall>)>::operator()[abi:ue170006](std::shared_ptr<yb::rpc::InboundCall>&&) ${YB_THIRDPARTY_DIR}/installed/asan/libcxx/include/c++/v1/__functional/function.h:192:16
    yugabyte#19 0x7fd9a91098ec in std::__function::__func<yb::tserver::TabletServerServiceIf::InitMethods(scoped_refptr<yb::MetricEntity> const&)::$_0, std::allocator<yb::tserver::TabletServerServiceIf::InitMethods(scoped_refptr<yb::MetricEntity> const&)::$_0>, void (std::shared_ptr<yb::rpc::InboundCall>)>::operator()(std::shared_ptr<yb::rpc::InboundCall>&&) ${YB_THIRDPARTY_DIR}/installed/asan/libcxx/include/c++/v1/__functional/function.h:363:12
    yugabyte#20 0x7fd9a9108b34 in std::__function::__value_func<void (std::shared_ptr<yb::rpc::InboundCall>)>::operator()[abi:ue170006](std::shared_ptr<yb::rpc::InboundCall>&&) const ${YB_THIRDPARTY_DIR}/installed/asan/libcxx/include/c++/v1/__functional/function.h:517:16
    yugabyte#21 0x7fd9a9108b34 in std::function<void (std::shared_ptr<yb::rpc::InboundCall>)>::operator()(std::shared_ptr<yb::rpc::InboundCall>) const ${YB_THIRDPARTY_DIR}/installed/asan/libcxx/include/c++/v1/__functional/function.h:1168:12
    yugabyte#22 0x7fd9a9108b34 in yb::tserver::TabletServerServiceIf::Handle(std::shared_ptr<yb::rpc::InboundCall>) ${BUILD_ROOT}/src/yb/tserver/tserver_service.service.cc:831:3
    yugabyte#23 0x7fd9a5b7a892 in yb::rpc::ServicePoolImpl::Handle(std::shared_ptr<yb::rpc::InboundCall>) ${YB_SRC_ROOT}/src/yb/rpc/service_pool.cc:269:19
    yugabyte#24 0x7fd9a59fcea5 in yb::rpc::InboundCall::InboundCallTask::Run() ${YB_SRC_ROOT}/src/yb/rpc/inbound_call.cc:317:13
    yugabyte#25 0x7fd9a5bad15d in yb::rpc::(anonymous namespace)::Worker::Execute() ${YB_SRC_ROOT}/src/yb/rpc/thread_pool.cc:115:15
    yugabyte#26 0x7fd9a42ad037 in std::__function::__value_func<void ()>::operator()[abi:ue170006]() const ${YB_THIRDPARTY_DIR}/installed/asan/libcxx/include/c++/v1/__functional/function.h:517:16
    yugabyte#27 0x7fd9a42ad037 in std::function<void ()>::operator()() const ${YB_THIRDPARTY_DIR}/installed/asan/libcxx/include/c++/v1/__functional/function.h:1168:12
    yugabyte#28 0x7fd9a42ad037 in yb::Thread::SuperviseThread(void*) ${YB_SRC_ROOT}/src/yb/util/thread.cc:895:3
    yugabyte#29 0x56176114abea in asan_thread_start(void*) ${YB_LLVM_TOOLCHAIN_DIR}/src/llvm-project/compiler-rt/lib/asan/asan_interceptors.cpp:225:31
    yugabyte#30 0x7fd99f1071c9 in start_thread (/lib64/libpthread.so.0+0x81c9) (BuildId: 1962602ac5dc3011b6d697b38b05ddc244197114)
    yugabyte#31 0x7fd99eb488d2 in clone (/lib64/libc.so.6+0x398d2) (BuildId: 37e4ac6a7fb96950b0e6bf72d73d94f3296c77eb)

UndefinedBehaviorSanitizer: undefined-behavior ../../src/yb/docdb/conflict_resolution.cc:865:5 in
```

IsolationLevel is left uninitialized at `PgsqlLockOperation::GetDocPaths` so the ASAN builds can get the `not a valid value` faliure.
Jira: DB-14458

Test Plan: advisory_lock-test

Reviewers: bkolagani

Reviewed By: bkolagani

Subscribers: ybase, yql

Differential Revision: https://phorge.dev.yugabyte.com/D40638

Author: Huqicheng

src/yb/docdb/pgsql_operation.cc

@@ -2591,6 +2591,8 @@ Status PgsqlLockOperation::Init(
 
 Status PgsqlLockOperation::GetDocPaths(GetDocPathsMode mode,
     DocPathsToLock *paths, IsolationLevel *level) const {
+  // Behaviour of advisory lock is regardless of isolation level.
+  *level = IsolationLevel::NON_TRANSACTIONAL;
   // kStrongReadIntents is used for acquring locks on the entire row.
   // It's duplicate with the primary intent for the advisory lock.
   if (mode != GetDocPathsMode::kStrongReadIntents) {