ci: Fix performance step in CI (#9926)

Author: mtrezza

.github/workflows/ci-performance.yml

@@ -326,5 +326,5 @@ jobs:
             echo "⚠️ Benchmark comparison not available" >> $GITHUB_STEP_SUMMARY
           fi
 concurrency:
-  group: ${{ github.workflow }}-${{ github.ref }}
+  group: ${{ github.workflow }}-${{ github.event.pull_request.number || github.ref }}
   cancel-in-progress: true