Clean-up temporary storage increase frontend

What does this MR do and why?

The https://gitlab.com/groups/gitlab-org/-/epics/3941+ epic has been closed as won't do, this MR is part of the clean-up.

The MR doesn't remove all related files completely, it removes all frontend changes and the related backend changes only.

Note: this MR doesn't include a changelog because it's removing a change behind a feature flag that hasn't been enabled.

Screenshots or screen recordings

before	after

How to set up and validate locally

1. In bin/rails console run
   • Feature.enable(:temporary_storage_increase) (if you work on storage related things make sure this condition is returning false)
   • ::Gitlab::CurrentSettings.update(enforce_namespace_storage_limit: true)
2. Navigate to a group's settings > usage quotas > storage
3. Observe there's no "Increase storage automatically" button

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 #385720