This makes the `Boards::CreateService` more reusable for EE
This is a backport of changes in https://gitlab.com/gitlab-org/gitlab-ee/merge_requests/2317
Do not update/delete: Banner broadcast message test data
Do not update/delete: Notification broadcast message test data
This is a backport of changes in https://gitlab.com/gitlab-org/gitlab-ee/merge_requests/2317