Provide reference ref for benchmark action and make it less spammy (#…

…3716)

* provide reference ref for benchmark action

it's apparently not possible to also provide a PR number for the comment
to target, since that is automically determined by the action (and wrong
for workflow_run workflows)

See also: benchmark-action/github-action-benchmark#250

* guard benchmark action with performance label again

This check was removed in #2774 for simplicity, bring it back to spam less

.github/workflows/benchmark.yml

@@ -19,6 +19,7 @@ concurrency:
 
 jobs:
   benchmark:
+    if: github.event_name != 'pull_request' || contains(github.event.pull_request.labels.*.name, 'performance')
     runs-on: ubuntu-latest
 
     steps:

.github/workflows/post-benchmark.yml

@@ -48,3 +48,4 @@ jobs:
           # Enable job summary
           summary-always: true
           comment-always: true
+          ref: ${{ github.event.workflow_run.head_sha }}