Don't show "guest" as a user grouping in Access > Users flyout menu

The "guest" item in the menu shown below is confusing and not useful for anything. Can it be removed?

<img width="432" height="198" alt="Image" src="https://github.com/user-attachments/assets/da4c86fb-9ddf-4ceb-b28e-62576a9fd37e" />

Somewhat related:
https://github.com/processwire/processwire-requests/issues/200
https://github.com/processwire/processwire-issues/issues/1310

