Adjust GHA workflows for branching

* Add `*.x` branch pattern to `merge-dependabot-pr.yml` and `pr-build.yml`
* Add `auto-cherry-pick.yml` and `backport-issue.yml` workflows

(cherry picked from commit e6e2a0d1d4)

.github/workflows/auto-cherry-pick.yml

@@ -0,0 +1,13 @@
+name: Auto Cherry-Pick
+
+on:
+  push:
+    branches:
+      - main
+      - '*.x'
+
+jobs:
+  cherry-pick-commit:
+    uses: spring-io/spring-github-workflows/.github/workflows/spring-cherry-pick.yml@v5
+    secrets:
+      GH_ACTIONS_REPO_TOKEN: ${{ secrets.GH_ACTIONS_REPO_TOKEN }}

.github/workflows/backport-issue.yml

@@ -0,0 +1,12 @@
+name: Backport Issue
+
+on:
+  push:
+    branches:
+      - '*.x'
+
+jobs:
+  backport-issue:
+    uses: spring-io/spring-github-workflows/.github/workflows/spring-backport-issue.yml@v5
+    secrets:
+      GH_ACTIONS_REPO_TOKEN: ${{ secrets.GH_ACTIONS_REPO_TOKEN }}

.github/workflows/merge-dependabot-pr.yml

@@ -4,6 +4,7 @@ on:
   pull_request:
     branches:
       - main
+      - '*.x'
 
 run-name: Merge Dependabot PR ${{ github.ref_name }}
 

.github/workflows/pr-build.yml

@@ -4,6 +4,7 @@ on:
   pull_request:
     branches:
       - main
+      - '*.x'
 
 jobs:
   build-pull-request: