Searching reviewers for an approval/CODEOWNERS should only be scoped to include user of that rule
## Problem
When searching for users from the a specific approval rule, it is searching across more users than the scoped list of users for that specific rule.
In the image below from `https://gitlab.com/gitlab-com/www-gitlab-com/-/merge_requests/142767`, `@mvanremmerden` is reviewer for an optional CODEOWNER rule, he should not appear in that dropdown.
{width=437 height=600}
## Expected behavior
Search is scoped to only those users who are eligible reviewers for that rule
## Related links
- Discussion of concerns of how the list of reviewers is currently retrieved https://gitlab.com/gitlab-org/gitlab/-/issues/481798#note_2166747535
issue