[BUGFIX] Followup to #51528

Because of some missing mocking there are
several DB error messages when running the FileTest

This adds the missing mocking of the MetaDataRepository.

Releases: 6.2
Resolves: #51528
Change-Id: I02ccb45d315b3eee045efda96c947fb67fd71d20
Reviewed-on: https://review.typo3.org/27215
Reviewed-by: Anja Leichsenring
Tested-by: Anja Leichsenring
Reviewed-by: Wouter Wolters
Tested-by: Wouter Wolters