[workflows] Update branch filter to allow actions on all 'release_*x' branches

By changing the branch filter from an explicit list to a glob, this commit
hopes to reduce future maintenance burden (as long as we continue to use
the same branch naming convention).

Author: bryanpkc

.github/workflows/flang-tests.yml

@@ -2,7 +2,8 @@ name: Build and test Flang
 
 on:
   pull_request:
-    branches: [ release_11x, release_12x, release_13x, release_14x ]
+    branches:
+      - 'release_*x'
 
 jobs:
   build:

.github/workflows/llvm-tests.yml

@@ -7,13 +7,13 @@ on:
   workflow_dispatch:
   push:
     branches:
-      - 'release/**'
+      - 'release_*x'
     paths:
       - 'llvm/**'
       - '.github/workflows/llvm-tests.yml'
   pull_request:
     branches:
-      - 'release/**'
+      - 'release_*x'
     paths:
       - 'llvm/**'
       - '.github/workflows/llvm-tests.yml'

.github/workflows/pre-compile_llvm.yml

@@ -3,7 +3,8 @@ name: Pre-compile llvm
 on:
   workflow_dispatch:
   push:
-    branches: [ release_11x, release_12x, release_13x, release_14x ]
+    branches:
+      - 'release_*x'
 
 jobs:
   build: