Reenables /user API request to return private-token if user is admin and requested with sudo

What does this MR do?

Reenables the API /users to return private-token when sudo is either a parameter or passed as a header and the user is admin.

Screenshots (if relevant)

Without sudo:

With sudo:

Does this MR meet the acceptance criteria?

• Changelog entry added
• Documentation created/updated
• API support added
• Tests
  • Added for this feature/bug
  • All builds are passing
• Conform by the merge request performance guides
• Conform by the style guides
• Branch has no merge conflicts with master (if it does - rebase it please)
• Squashed related commits together

What are the relevant issue numbers?

Closes #24537 (closed)