Adds internal SLA metric monitoring for pull mirroring.
This metric was suggested and was needed in order to Close https://gitlab.com/gitlab-org/gitlab-ee/issues/3641#note_42494954
Edited by username-removed-117638
Do not update/delete: Banner broadcast message test data
Do not update/delete: Notification broadcast message test data
This metric was suggested and was needed in order to Close https://gitlab.com/gitlab-org/gitlab-ee/issues/3641#note_42494954