[BUGFIX] Remove GU::fixPermissionsSetsGroup() test

This test checks lowlevel things like usergroup to
be changed by GeneralUtility::fixPermissions().
Various tests in this area have been disabled on
Windows already. They are problematic in macOS driven
docker as well since macOS heavily messes around with
access rights.
We give up on this now, and reduce the details test
checks of GeneralUtility::fixPermissions() a bit by
removing that test.

Resolves: #101568
Releases: main, 12.4, 11.5
Change-Id: I36e781302285dc1966633723abdc8f15bf84ef06
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/80382


Tested-by: core-ci <typo3@b13.com>
Tested-by: Christian Kuhn <lolli@schwarzbu.ch>
Reviewed-by: Christian Kuhn <lolli@schwarzbu.ch>