Chore: Skip more GHA jobs if backend files are not changed (#109803)

.github/workflows/swagger-gen.yml

@@ -14,10 +14,29 @@ concurrency:
   cancel-in-progress: true
 
 jobs:
+  detect-changes:
+    name: Detect whether code changed
+    runs-on: ubuntu-latest
+    permissions:
+      contents: read
+    outputs:
+      changed: ${{ steps.detect-changes.outputs.backend }}
+    steps:
+      - uses: actions/checkout@v4
+        with:
+          persist-credentials: true # required to get more history in the changed-files action
+          fetch-depth: 2
+      - name: Detect changes
+        id: detect-changes
+        uses: ./.github/actions/change-detection
+        with:
+          self: .github/workflows/swagger-gen.yml
+
   verify:
     name: Verify committed API specs match
     runs-on: ubuntu-latest
-    if: ${{ github.repository == 'grafana/grafana' }}
+    needs: detect-changes
+    if: github.repository == 'grafana/grafana' && needs.detect-changes.outputs.changed == 'true'
     permissions:
       contents: read # clone the repository
       id-token: write # required for Vault access