[BUGFIX][EM] TER repository page fails

After the persistence patch in extbase was reverted, em needs an
adaption to make the Repository tab work again.

Change-Id: If88f9c2e52fdeed344955a62568835b3968db5e2
Fixes: #46844
Related: #46837
Releases: 6.1
Reviewed-on: https://review.typo3.org/19497
Reviewed-by: Christian Kuhn
Tested-by: Christian Kuhn