[Improvement] Cannot select user groups when suggesting private permissions for the knowledge base.

### Improvement Description

<img width="934" height="686" alt="Image" src="https://github.com/user-attachments/assets/5d4dbf71-b0b7-44e8-8316-2007ec62b05e" />
@SimengBian  私有时，建议用户组置灰