Requarantine failing test

This test was quarantined, but was unquarantined when a bug in the
test was fixed. However, there's still a bug in the application code
so the test still fails.

qa/qa/specs/features/ee/browser_ui/3_create/repository/file_locking_spec.rb

@@ -59,8 +59,7 @@ module QA
         end
       end
 
-      # Known issue: https://gitlab.com/gitlab-org/gitlab/issues/40125
-      it 'creates a merge request and fails to merge' do
+      it 'creates a merge request and fails to merge', quarantine: { issue: 'https://gitlab.com/gitlab-org/gitlab/issues/40125', type: :bug } do
         push branch: 'test', as_user: @user_one
 
         merge_request = Resource::MergeRequest.fabricate_via_api! do |merge_request|