Fix storage migration check for non-empty queues

What does this MR do?

In https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/25976 we've implemented a check to prevent running the rake task while an opposite operation is still running/scheduled. The problem is that the API used works only in test mode. 🤦

This fixes the tests and switch to a code that can run in production.

What are the relevant issue numbers?

https://gitlab.com/gitlab-org/gitlab-ce/issues/58739

Does this MR meet the acceptance criteria?

• Tests added for this feature/bug
• Conforms to the code review guidelines
• Conforms to the merge request performance guidelines
• Conforms to the style guides

Closes #58739 (closed)