Remove redundant `require`s from Banzai files
We're trying to avoid circular dependency errors.
Related: https://gitlab.com/gitlab-org/gitlab-ce/issues/13521
Sentry: https://sentry.gitlap.com/gitlab/gitlabcom/issues/8/
Do not update/delete: Banner broadcast message test data
Do not update/delete: Notification broadcast message test data
We're trying to avoid circular dependency errors.
Related: https://gitlab.com/gitlab-org/gitlab-ce/issues/13521
Sentry: https://sentry.gitlap.com/gitlab/gitlabcom/issues/8/