Prevent URL concatenation for avatars

What does this MR do?

Fixes avatar URL concatenation that includes templated value.

Are there points in the code the reviewer needs to double check?

This fix requires to be tested in CDN-enabled environment before signing it off for production

Does this MR meet the acceptance criteria?

• Changelog entry added, if necessary
• [ ] Documentation created/updated
• [ ] API support added
• [ ] Tests added for this feature/bug
• Review
  • [ ] Has been reviewed by UX
  • [ ] Has been reviewed by Frontend
  • Has been reviewed by Backend
  • [ ] Has been reviewed by Database
• Conform by the merge request performance guides
• Conform by the style guides
• Squashed related commits together

What are the relevant issue numbers?

Closes #38189 (closed)