ci: Only comment on alert.

This posts the whole benchmark results, which can be spammy.

Author: jaqx0r

.github/workflows/benchmark.yml

@@ -33,5 +33,5 @@ jobs:
           external-data-json-path: ./cache/benchmark-data.json
           save-data-file: ${{ github.event_name != 'pull_request' }}
           github-token: ${{ secrets.GITHUB_TOKEN }}
-          comment-always: true
+          comment-on-alert: true
           summary-always: true