Update the role UI to correctly reflect the current behavior for tokens

In Central Dogma, the GUEST role is limited to authenticated users and is not granted to new tokens. https://github.com/line/centraldogma/pull/1093
It would be nicer to clarify this behavior in the UI.

<img width="967" height="453" alt="Image" src="https://github.com/user-attachments/assets/9c901589-f48b-4846-b5c6-564d2f73265a" />