Try and get reposync branch updated on a cron (#16866)

Get repo sync updated on a cron as some extra hardening

Co-authored-by: Chiedo <chiedo@users.noreply.github.com>
Co-authored-by: James M. Greene <JamesMGreene@github.com>

.github/workflows/autoupdate-repo-sync-branch-on-cron.yml

@@ -0,0 +1,14 @@
+name: autoupdate reposync branch on cron
+on:
+  schedule:
+    - cron: '*/5 * * * *'
+  autoupdate:
+    name: autoupdate
+    runs-on: ubuntu-18.04
+    steps:
+      - uses: docker://chinthakagodawita/autoupdate-action:v1
+        env:
+          GITHUB_TOKEN: ${{ secrets.OCTOMERGER_PAT_WITH_REPO_AND_WORKFLOW_SCOPE }}
+          PR_FILTER: labelled
+          PR_LABELS: 'automated-reposync-pr'
+          MERGE_MSG: "Branch was updated using the 'autoupdate reposync branch on cron' Actions workflow."

.github/workflows/repo-sync.yml

@@ -52,7 +52,7 @@ jobs:
           destination_branch: main
           pr_title: 'repo sync'
           pr_body: "This is an automated pull request to sync changes between the public and private repos.\n\n:robot: This pull request should be merged (not squashed) to preserve continuity across repos, so please let a bot do the merging!"
-          pr_label: automerge,autoupdate
+          pr_label: automerge,autoupdate,automated-reposync-pr
           github_token: ${{ secrets.OCTOMERGER_PAT_WITH_REPO_AND_WORKFLOW_SCOPE }}
 
       - name: Find pull request