Merge branch 'default_enable_store_merge_request_line_metrics_ff' into 'master'

Enable store_merge_request_line_metrics FF

See merge request gitlab-org/gitlab!29483

ee/lib/analytics/merge_request_metrics_calculator.rb

@@ -19,7 +19,7 @@ module Analytics
 
     # rubocop: disable CodeReuse/ActiveRecord
     def line_counts_data
-      return {} if Feature.disabled?(:store_merge_request_line_metrics, merge_request.target_project)
+      return {} if Feature.disabled?(:store_merge_request_line_metrics, merge_request.target_project, default_enabled: true)
 
       {
         added_lines: raw_diff_files.sum(&:added_lines),