auth: Clarify error message
This message can be hit in a variety of accidental ways, so clarify it
probably means someone is inputting an invalid build name.
Bug: T353583
How to register an account on GitLab. To prevent spam, new accounts are locked until approved by an admin or the approver bot. You can also file an unlock request to expedite access.
Support: mw:GitLab, how to host a project on GitLab, #wikimedia-gitlab on libera.chat, #GitLab on Phabricator.
This message can be hit in a variety of accidental ways, so clarify it
probably means someone is inputting an invalid build name.
Bug: T353583