Cleanup Feature Flag: usage_quotas_for_all_editions

What does this MR do and why?

Implements: #371639 (closed)

This MR is a clean up of the Feature Flag usage_quotas_for_all_editions

More details of the whole feature development in the epic: &7176 (closed)

MR acceptance checklist

Please evaluate this MR against the MR acceptance checklist. It helps you analyze changes to reduce risks in quality, performance, reliability, security, and maintainability.

Screenshots or screen recordings

GitLab CE	GitLab EE

How to set up and validate locally

1. Visit any Group Usage Quotas: https://gdk.test:3443/groups/<group-id>/-/usage_quotas
2. Make sure the page loads fine