Filter commented_approvers for user note authors

What does this MR do and why?

Previously, we were pulling authors of all notes, including system notes (such as cross-MR and Issue mentions).

Screenshots or screen recordings

Before

After

How to set up and validate locally

Numbered steps to set up and validate the change are strongly suggested.

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 #353387 (closed)