[yugabyte#4851] Default to IPv4 addresses only for resolution and local addr selection

Summary:
In yugabyte@5a88e2f, a getaddrinfo call was changed to use AF_UNSPEC instead of AF_INET to return both IPv4 and IPv6 results for resolution. This means that localhost now resolves to both 127.0.0.1 and [::1] on most modern systems that have these entries in /etc/hosts.

However, in https://github.com/yugabyte/yugabyte-db/runs/787021393, it seems there is a github workflow host that resolves localhost to [::1] but has an error binding to [::1].

The issue doesn't happen on a vanilla Ubuntu 18.04 GCP host with a similar IPv6 entry added for localhost. I'm not sure how many hosts exist with this issue but to be safe, I am restricting DNS resolution and local address seletion to only use IPv4 hosts. This behavior should be roughly similar to earlier.

Test Plan: Ran this fix through the workflow as part of a PR and verified that the create snapshot failure no longer occurs.

Reviewers: bogdan, sergei, mikhail

Reviewed By: mikhail

Subscribers: ybase

Differential Revision: https://phabricator.dev.yugabyte.com/D8734

Author: iSignal

src/yb/rpc/rpc_stub-test.cc

@@ -760,6 +760,8 @@ TEST_F(RpcStubTest, TestRpcPerformance) {
 }
 
 TEST_F(RpcStubTest, IPv6) {
+  google::FlagSaver saver;
+  FLAGS_net_address_filter = "all";
   std::vector<IpAddress> addresses;
   GetLocalAddresses(&addresses, AddressFilter::ANY);
 

src/yb/util/net/net_util.cc

@@ -81,7 +81,7 @@ using strings::Substitute;
 
 DEFINE_string(
     net_address_filter,
-    "ipv4_external,ipv4_all,ipv6_external,ipv6_non_link_local,all",
+    "ipv4_external,ipv4_all",
     "Order in which to select ip addresses returned by the resolver"
     "Can be set to something like \"ipv4_all,ipv6_all\" to prefer IPv4 over "
     "IPv6 addresses."