Updates to performance page
Per comments in https://gitlab.com/gitlab-com/www-gitlab-com/merge_requests/6250 that were unresolved in that merge request.
Do not update/delete: Banner broadcast message test data
Do not update/delete: Notification broadcast message test data
Per comments in https://gitlab.com/gitlab-com/www-gitlab-com/merge_requests/6250 that were unresolved in that merge request.