[BUGFIX] Followup to #53691 Failing unit test

Remove a duplicate mocking in test fileIndexStatusIsTrueIfUidIsSet()
and setUp() triggered as side effect after patch 71eb69ed230a.

Resolves: #53691
Releases: 6.2
Change-Id: I8ac96d9157bf946bba3c9561369f3553d459f275
Reviewed-on: https://review.typo3.org/27223
Reviewed-by: Christian Kuhn
Tested-by: Christian Kuhn
Reviewed-by: Helmut Hummel
Tested-by: Helmut Hummel