Update gitlab_git to 7.2.8.
Addresses #2037 (closed) and internal https://dev.gitlab.org/gitlab/gitlabhq/issues/2421.
Do not update/delete: Banner broadcast message test data
Do not update/delete: Notification broadcast message test data
Addresses #2037 (closed) and internal https://dev.gitlab.org/gitlab/gitlabhq/issues/2421.