Move `compile_changelog` to `GitlabCeRelease`
After https://gitlab.com/gitlab-org/release-tools/merge_requests/54,
there was no reason for this method to be in BaseRelease
because it's
only called in one place.
Do not update/delete: Banner broadcast message test data
Do not update/delete: Notification broadcast message test data
After https://gitlab.com/gitlab-org/release-tools/merge_requests/54,
there was no reason for this method to be in BaseRelease
because it's
only called in one place.