[BUGFIX] Register suite integrity tests again

The integrity unit tests executed at the very bottom of the
test suite very accidentally removed during issue #40950.
Add them again.

Change-Id: Ifc59f201c98a79e1cf376e1c1e1124408cd37c10
Fixes: #44936
Related: #40950
Releases: 6.1, 6.0
Reviewed-on: https://review.typo3.org/17808
Reviewed-by: Christian Kuhn
Tested-by: Christian Kuhn