chore: restore backport creator workflow (#14156)

Signed-off-by: Edward Welch <[email protected]>
Co-authored-by: Trevor Whitney <[email protected]>

.github/workflows/backport.yml

@@ -0,0 +1,34 @@
+name: Backport PR Creator
+on:
+  pull_request_target:
+    types:
+      - closed
+      - labeled
+
+jobs:
+  main:
+    if: github.repository == 'grafana/loki'
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout Actions
+        uses: actions/checkout@v4
+        with:
+          repository: "grafana/grafana-github-actions"
+          path: ./actions
+          ref: main
+      - name: Install Actions
+        run: npm install --production --prefix ./actions
+      - id: "get_github_app_token"
+        name: "get github app token"
+        uses: "actions/create-github-app-token@v1"
+        with:
+          app-id: "${{ secrets.APP_ID }}"
+          owner: "${{ github.repository_owner }}"
+          private-key: "${{ secrets.APP_PRIVATE_KEY }}"
+      - name: Run backport
+        uses: ./actions/backport
+        with:
+          metricsWriteAPIKey: ${{secrets.GRAFANA_MISC_STATS_API_KEY}}
+          token: ${{ steps.get_github_app_token.outputs.token }}
+          labelsToAdd: "backport"
+          title: "chore: [{{base}}] {{originalTitle}}"