[CI] Add auto approval/merge for helm weekly release (#10254)

* add autoreview for helm release

* change action name

.github/workflows/grafanabot_reviewer.yml

@@ -0,0 +1,36 @@
+name: Auto-review Grafanabot PRs
+on: pull_request_target
+
+permissions:
+  pull-requests: write
+  contents: write
+
+jobs:
+  dependabot-reviewer:
+    runs-on: ubuntu-latest
+
+    if: ${{ github.event.pull_request.user.login == 'grafanabot' }}
+
+    steps:
+      - name: Checkout Repository
+        uses: actions/checkout@v4
+
+      - name: Approve and auto-merge
+        id: auto-merge
+        if: contains(github.event.pull_request.head.ref, 'helm-chart-weekly-')
+        run: |
+          gh pr merge --auto --squash "$PR_URL"
+          gh pr review $PR_URL \
+          --approve -b "**I'm approving** this pull request, since it is a helm release."
+        env:
+          PR_URL: ${{github.event.pull_request.html_url}}
+          GITHUB_TOKEN: ${{secrets.GH_BOT_ACCESS_TOKEN}}
+
+      - name: Manual review is required
+        if: steps.auto-merge.conclusion != 'success'
+        run: |
+          gh pr comment $PR_URL --body "**This PR from grafanabot requires manual review.**"
+
+        env:
+          PR_URL: ${{github.event.pull_request.html_url}}
+          GITHUB_TOKEN: ${{secrets.GITHUB_TOKEN}}