Please add a rake task or other admin endpoint for clearing the rack-attack cache

Description

If an IP currently gets added to the rack-attack list, there is no way to clear it absent waiting it out. Would like to see an option in the UI to flush that cache.

Proposal

Add either a rake task or something in the admin settings page to allow immediate flush of single or all IPs from that cache.

Links / references

https://gitlab.com/gitlab-org/gitlab-ce/issues/24664

Documentation blurb

Overview

  • What is the underlying (business) problem?

In my case, this was triggered by a missed/incorrect ssh agent session combined with a bulk deploy to large numbers of hosts that were pulling from our gitlab-ce server.

  • How do you use this feature?

If for whatever reason a host gets incorrectly (or correctly, but not desired) added to the list, you can reset/flush the cache using this option.

Use cases

Administrators that need to clear the cache of rack-attack blocked users/hosts.

Feature checklist

Make sure these are completed before closing the issue, with a link to the relevant commit.