debug: cancel only benchmark jobs on concurrency

Author: franckgaga

.github/workflows/benchmark.yml

@@ -4,9 +4,7 @@ on:
     branches: [ main ]
     types: [labeled, opened, synchronize, reopened]
 concurrency:
-  # Skip intermediate builds: always.
-  # Cancel intermediate builds: only if it is a pull request build.
-  group: ${{ github.workflow }}-${{ github.ref }}
+  group: benchmark-${{ github.ref }}
   cancel-in-progress: ${{ startsWith(github.ref, 'refs/pull/') }}
 permissions:
   pull-requests: write    # needed to post comments