Docs: Reference to closed issue needs to be updated

Problem to solve

The Code Owners page: https://gitlab.com/gitlab-org/gitlab/-/blob/master/doc/user/project/code_owners.md

Has a reference to a closed issue on lines 196-200:

Optional sections in the `CODEOWNERS` file are treated as optional only
when changes are submitted by using merge requests. If a change is submitted directly
to the protected branch, approval from Code Owners is still required, even if the
section is marked as optional. [An issue exists](https://gitlab.com/gitlab-org/gitlab/-/issues/297638)
to allow direct pushes to the protected branch for sections marked as optional.

The issue is closed, so this section should be updated based on the latest functionality.