Instrument the HousekeepingService class
I'm starting with instrumenting this class as mentioned in https://gitlab.com/gitlab-org/gitlab-ce/issues/15094#note_4796278.
Do not update/delete: Banner broadcast message test data
Do not update/delete: Notification broadcast message test data
I'm starting with instrumenting this class as mentioned in https://gitlab.com/gitlab-org/gitlab-ce/issues/15094#note_4796278.