Add link to feedback issue

What does this MR do and why?

Adds a link to feedback issue in ai chat experiment

Screenshots or screen recordings

How to set up and validate locally

1. Enable the following feature flags:
   • explain_code
   • explain_code_snippet
   • openai_experimentation
   • ai_experimentation_api
2. Open a file containing Source Code (Note, this file should not be from the GitLab codebase).
   • sample_file.js
3. Highlight some of the Source Code.
4. Click on the (?) button in the gutter to the left of the source code.
5. A popup should appear with the link to feedback issue in the bottom.

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.

Related to #407205