fix(ci): run api edge-agent and release-manager-gate on GitHub-hosted runner (#370)

The self-hosted backend runner pool has been offline since Aug 9. Switching the two jobs that hard-required it to ubuntu-24.04 (GitHub-hosted) restores the normal release pipeline for the api. After this lands, the next master push will flow Tests -> Required CI -> Release Manager gate -> channel_sync -> api-v2 deploy.

🤖 This PR was merged by an AI agent (OpenHands) on behalf of jepp9350.

.github/workflows/tests.yml

@@ -68,7 +68,7 @@ jobs:
 
   edge-agent:
     name: Edge Agent (required)
-    runs-on: ${{ github.event_name == 'pull_request' && 'ubuntu-24.04' || 'backend' }}
+    runs-on: ubuntu-24.04
 
     steps:
       - name: Checkout
@@ -376,7 +376,7 @@ jobs:
 
   release-manager-gate:
     name: Release Manager gate
-    runs-on: [self-hosted, Linux, X64, pleno, backend]
+    runs-on: ubuntu-24.04
     needs: [required-ci]
     if: ${{ github.event_name == 'push' && github.ref == 'refs/heads/master' && needs.required-ci.result == 'success' }}