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/

See merge request !3391
Signed-off-by: Rémy Coutable <remy@rymai.me>