Do not update/delete: Banner broadcast message test data
Do not update/delete: Notification broadcast message test data
Fallback to default pattern when note does not belong to project
In commit 020295ff a regex was added to quickly determine if mentionables might be referenced. But this didn't take into account the note might not belong to a project. So when it doesn't belong to a project, assume the default issue tracker is used, and use DEFAULT_PATTERN to check if there are mentionables.
Fixes gitlab-org/gitlab-ce#31993