Enhance changelog workflow to check for missing labels

Signed-off-by: Kunal Kotwani <[email protected]>

.github/workflows/changelog_verifier.yml

@@ -6,7 +6,7 @@ on:
 jobs:
   # Enforces the update of a changelog file on every pull request
   verify-changelog:
-    if: github.repository == 'opensearch-project/OpenSearch'
+#    if: github.repository == 'opensearch-project/OpenSearch'
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v4
@@ -27,5 +27,12 @@ jobs:
         continue-on-error: true
       - run: |
           if [[ ${{ steps.verify-changelog-3x.outcome }} == 'failure' && ${{ steps.verify-changelog.outcome }} == 'failure' ]]; then
+            echo "error: Please ensure a changelog entry exists in CHANGELOG.md or CHANGELOG-3.0.md"
+            exit 1
+          fi
+          
+          labels=${{ github.event.pull_request.labels.*.name }}
+          if [[ ${{ steps.verify-changelog.outcome }} == 'success' && ! $labels =~ "backport" ]]; then
+            echo "error: Please make sure that the PR has a backport label associated with it when making an entry to the CHANGELOG.md file"
             exit 1
           fi