ci(github): tweak parallelism in build-test-distribute (#9760)

What was happening:

1. New push on PRs cancelled previous runs
2. Commits on branches would run in parallel

What happens now:

1. Unchanged from before
2. Commits on branches run CI one after the other

This should help streamline CI runs favouring the oldest merge first

Signed-off-by: Charly Molter <[email protected]>

.github/workflows/build-test-distribute.yaml

@@ -6,8 +6,8 @@ on:
   pull_request:
     branches: ["master", "release-*"]
 concurrency:
-  group: ${{ github.head_ref || github.run_id }}
-  cancel-in-progress: true
+  group: ${{github.workflow}}-${{ github.ref_name }} # group all runs by branch or tag
+  cancel-in-progress: ${{ github.event_name == 'pull_request' }} # only cancel previous runs on PRs, we want each commit to build on branches
 permissions:
   contents: write # To upload assets
   id-token: write # For using token to sign images