Increase free drive STALE threshold to 4 hours

Currently, as discussed in https://gitlab.cern.ch/cta/operations/-/issues/929, the drive is marked as STALE after 10 minutes only.

As written in the same issue, we decided to:

• Mark as STALE a Free drive that did not update its status in the past 4 hours
• Rest of code unchanged

This change is minimal, only part of cta-admin command output for operators.