Resolve stretched avatars

What does this MR do and why?

Fixes #366595 - avatars are stretched if the source image is not square.

Screenshots or screen recordings

See #366595

The demo-avatar project can be used as a reference: https://gitlab.com/argentum-systems

Before

If the avatar image isn't square, then the result will be a stretched image to fill the box. This occurs in project lists and instant search results.

After

Here, the "Hello" text has been restored to its original shape

MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

• I have evaluated the MR acceptance checklist for this MR.