CI: Backport to release branches (#100067)

* update backport and release comms

* Backport to release branches and change docs source branch for publishing

* Add new workflows to CODEOWNERS

* Re-add removed line oops

* backport-testing -> grafana

* checkout grafana repo in backport action, reference repo / branch in reusable action

* generate -> create

.github/workflows/release-pr.yml

@@ -4,7 +4,7 @@
 # Please refrain from including any processes that do not result in code changes in this workflow. Instead, they should
 # either be triggered in the release promotion process or in the release comms process (that is triggered by merging
 # this PR).
-name: Complete a Grafana release
+name: Grafana Release PR
 on:
   workflow_dispatch:
     inputs:
@@ -19,7 +19,7 @@ on:
       target:
         required: true
         type: string
-        description: The base branch that these changes are being merged into
+        description: The release branch pattern (eg v9.5.x) that these changes are being merged into
       backport:
         required: false
         type: string
@@ -61,10 +61,17 @@ jobs:
         with:
           app_id: ${{ secrets.GRAFANA_DELIVERY_BOT_APP_ID }}
           private_key: ${{ secrets.GRAFANA_DELIVERY_BOT_APP_PEM }}
+      - name: Get release branch
+        id: branch
+        uses: grafana/grafana-github-actions-go/latest-release-branch@main
+        with:
+          token: ${{ steps.generate_token.outputs.token }}
+          ownerRepo: 'grafana/grafana'
+          pattern: ${{ inputs.target }}
       - name: Checkout Grafana
         uses: actions/checkout@v4
         with:
-          ref: ${{ inputs.target }}
+          ref: ${{ steps.branch.outputs.branch }}
           fetch-depth: 0
           fetch-tags: true
       - name: Checkout Grafana (main)
@@ -124,7 +131,6 @@ jobs:
           rm -f CHANGELOG.part changelog_items.md
 
           git diff CHANGELOG.md
-          
       - name: "Prettify CHANGELOG.md"
         run: npx prettier --write CHANGELOG.md
       - name: Commit CHANGELOG.md changes
@@ -151,7 +157,7 @@ jobs:
             $( [ "x${{ inputs.latest }}" == "xtrue" ] && printf %s '-l "release/latest"') \
             -l "no-changelog" \
             --dry-run=${{ inputs.dry_run }} \
-            -B "${{ inputs.target }}" \
+            -B "${{ steps.branch.outputs.branch }}" \
             --title "Release: ${{ inputs.version }}" \
             --body "These code changes must be merged after a release is complete"
         env:
@@ -165,7 +171,7 @@ jobs:
             -l "product-approved" \
             -l "no-changelog" \
             --dry-run=${{ inputs.dry_run }} \
-            -B "${{ inputs.target }}" \
+            -B "${{ steps.branch.outputs.branch }}" \
             --title "Release: ${{ inputs.version }}" \
             --body "These code changes must be merged after a release is complete"
         env: