[BUGFIX] Reanimate unit tests

Make phpunit backend module for extbase tests load again

Change-Id: Ib3e05e343d2f34185c52727f16ede1331332b7ca
Resolves: #40135
Related: #40095
Releases: 6.0
Reviewed-on: http://review.typo3.org/14046
Reviewed-by: Christian Kuhn
Tested-by: Christian Kuhn