[TASK] Split an unhappy unit test

The test setup used a dataProvider and in order to get it's own
setup right, it reverses and resets leftover instances from the
previous run. It is way easier to split the test setup according
the admin flag, that decides about the resets, and run on a
clear dedicated environment.

Additionally, the system under test is in itself a mocked instance,
which is neither necessary in this case, nor generally recommended.
The mock has been resolved.

Resolves: #103901
Releases: main, 12.4, 11.5
Change-Id: If40ef38a0e0fc2e73dd5f0bc8caff923cc48d661
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/84385


Reviewed-by: Oliver Klee <typo3-coding@oliverklee.de>
Tested-by: core-ci <typo3@b13.com>
Tested-by: Christian Kuhn <lolli@schwarzbu.ch>
Reviewed-by: Stefan Bürk <stefan@buerk.tech>
Tested-by: Oliver Klee <typo3-coding@oliverklee.de>
Reviewed-by: Christian Kuhn <lolli@schwarzbu.ch>
Tested-by: Stefan Bürk <stefan@buerk.tech>