Do not update/delete: Banner broadcast message test data
Do not update/delete: Notification broadcast message test data
Closes #15527 (closed), #15569 (closed), #15623 (closed), #15630 (closed), #15637 (closed), #15653 (closed), #15870 (closed), #16558 (closed), #16875 (closed), #16987 (closed), #17016 (closed), https://github.com/gitlabhq/gitlabhq/issues/10317.