Remove the email subject prefix
This changes email subjects from: GitLab | Team / Project | Note for issue #1234 to: Team / Project | Note for issue #1234 Rationale: * Emails should be as meaningful as possible, and emphasize content over chrome. The "GitLab" name is more chrome than content. * Users can tell an email coming from GitLab by the sender or the header in the email content. * An organization that works mainly with GitLab knows that every SVC email comes from GitLab. For these organizations, having "GitLab" in front of every email is just noise hiding the meaningful information.