Disable archive rate limit by default

Some users depend on having a high number of unauthenticated archive
downloads.  Make this feature flag off by default until we have a chance
to ship a way to toggle this off in the admin panel.

changelogs/unreleased/sh-disable-archive-rate-throttle-default.yml

+---
+title: Disable archive rate limit by default
+merge_request: 28264
+author:
+type: fixed

lib/gitlab/rate_limit_helpers.rb

@@ -7,7 +7,7 @@ module Gitlab
     ARCHIVE_RATE_THROTTLE_KEY = :project_repositories_archive
 
     def archive_rate_limit_reached?(user, project)
-      return false unless Feature.enabled?(:archive_rate_limit, default_enabled: true)
+      return false unless Feature.enabled?(:archive_rate_limit)
 
       key = ARCHIVE_RATE_THROTTLE_KEY