Turn on feature flag for the code review aggregated metrics

changelogs/unreleased/turn_on_aggregated_code_review_metrics.yml

+---
+title: Aggregate code review metrics
+merge_request: 56734
+author:
+type: other

config/feature_flags/development/usage_data_code_review_aggregation.yml

@@ -5,4 +5,4 @@ rollout_issue_url:
 milestone: '13.9'
 type: development
 group: group::code review
-default_enabled: false
+default_enabled: true