text: Title: [BUG] Unable to remove user group from permissions
  Body: ### Description
  
  When removing a user group from the permission panel, it is ignored on reload. Even when using bulk edit.
  
  ### Steps to reproduce
  
  1. Add two or more user groups:
    ![Image](https://github.com/user-attachments/assets/dd44bd08-ee24-40bf-a2ed-5cc726fe0670)
  2. Remove one of these groups and hit save:
    ![Image](https://github.com/user-attachments/assets/007c4f2b-a7dd-4b7d-b2fe-9eb14c3d9d41)
  3. Reload the page or switch to another document and back: the removed user group returned
  
  ### Webserver logs
  
  ```bash
  nothing interesting here
  ```
  
  ### Browser logs
  
  ```bash
  nothing interesting here
  ```
  
  ### Paperless-ngx version
  
  2.14.7
  
  ### Host OS
  
  Linux-6.8.0-54-generic-x86_64-with-glibc2.39
  
  ### Installation method
  
  Bare metal
  
  ### System status
  
  ```json
  {
      "pngx_version": "2.14.7",
      "server_os": "Linux-6.8.0-54-generic-x86_64-with-glibc2.39",
      "install_type": "bare-metal",
      "storage": {
          "total": 61106941952,
          "available": 42460422144
      },
      "database": {
          "type": "postgresql",
          "url": "paperless",
          "status": "OK",
          "error": null,
          "migration_status": {
              "latest_migration": "paperless_mail.0001_initial_squashed_0009_mailrule_assign_tags",
              "unapplied_migrations": []
          }
      },
      "tasks": {
          "redis_url": "redis://localhost:6379",
          "redis_status": "OK",
          "redis_error": null,
          "celery_status": "OK",
          "index_status": "OK",
          "index_last_modified": "2025-03-05T13:33:41.056123Z",
          "index_error": null,
          "classifier_status": "OK",
          "classifier_last_trained": null,
          "classifier_error": null
      }
  }
  ```
  
  ### Browser
  
  Chrome
  
  ### Configuration changes
  
  nothing major was changed, I don't think there is something interesting here
  
  ### Please confirm the following
  
  - [x] I believe this issue is a bug that affects all users of Paperless-ngx, not something specific to my installation.
  - [x] This issue is not about the OCR or archive creation of a specific file(s). Otherwise, please see above regarding OCR tools.
  - [x] I have already searched for relevant existing issues and discussions before opening this report.
  - [x] I have updated the title field above with a concise description.