Merge branch '438053-cleanup-frontend-issues-completed-ff-code' into 'master'

Cleanup issues_completed_analytics_feature_flag FF

See merge request https://gitlab.com/gitlab-org/gitlab/-/merge_requests/146860



Merged-by: Brandon Labuschagne <blabuschagne@gitlab.com>
Approved-by: Brandon Labuschagne <blabuschagne@gitlab.com>
Approved-by: Rudy Crespo <rcrespo@gitlab.com>
Co-authored-by: Adam Hegyi <ahegyi@gitlab.com>