Fix performance issues with 'cta-admin dr down' command

Description

Instead of retrieving all drive configurations and filtering them in a separate step, we now use a tailored database query that directly retrieves the drive names associated with the scheduler backend name of the frontend. The performance has been tested locally, results can be seen in the comment of the issue #1185 (closed).

Checklist

• Documentation reflects the changes made.
• Merge Request title is clear, concise, and suitable as a changelog entry. See this link

References

Closes #1185 (closed)