tools: simplify notify-on-push

Now that we have the repo setup to reject commits that do not contain
any metadata, we can remove the custom logic that was trying to catch
commits merged using the default commit message.

PR-URL: https://github.com/nodejs/node/pull/61050
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>

.github/workflows/notify-on-push.yml

@@ -27,36 +27,20 @@ jobs:
           SLACK_USERNAME: nodejs-bot
           SLACK_WEBHOOK: ${{ secrets.SLACK_WEBHOOK }}
 
-  notifyOnMissingMetadata:
-    name: Notify on Push on `main` that lacks metadata
+  validateCommitMessage:
+    name: Notify on Push on `main` with invalid message
     if: github.repository == 'nodejs/node'
     runs-on: ubuntu-latest
-    permissions:
-      contents: read
-      pull-requests: write
     steps:
       - uses: actions/checkout@1af3b93b6815bc44a9784bd300feb67ff0d1eeb3  # v6.0.0
         with:
           persist-credentials: false
       - name: Check commit message
-        run: npx -q core-validate-commit ${{ github.event.after }} || echo "INVALID_COMMIT_MESSAGE=1" >> $GITHUB_ENV
-      - name: Retrieve PR number if possible
-        if: env.INVALID_COMMIT_MESSAGE
-        run: |
-          COMMIT_TITLE=$(git --no-pager log --oneline -1 --no-color) node <<'EOF' >> $GITHUB_ENV || true
-          const invalidCommitMessageMatch = /\s\(\#(\d+)\)$/.exec(process.env.COMMIT_TITLE);
-          if (invalidCommitMessageMatch == null) process.exit(1)
-          console.log(`PR_ID=${invalidCommitMessageMatch[1]}`)
-          EOF
-      - name: Comment on the Pull Request
-        if: ${{ env.PR_ID }}
-        run: |
-          gh pr comment ${{ env.PR_ID }} --repo "${{ github.repository }}" \
-            --body "A commit referencing this Pull Request was pushed to `${{ github.ref_name }}` by @${{ github.actor }} with an invalid commit message."
+        run: npx -q core-validate-commit "$COMMIT"
         env:
-          GH_TOKEN: ${{ github.token }}
+          COMMIT: ${{ github.event.after }}
       - name: Slack Notification
-        if: ${{ env.INVALID_COMMIT_MESSAGE }}
+        if: failure()
         uses: rtCamp/action-slack-notify@e31e87e03dd19038e411e38ae27cbad084a90661  # 2.3.3
         env:
           SLACK_COLOR: '#DE512A'