[BUGFIX] Tests: Remove some useless tests

Some tests of GeneralUtility depend on LocalConfiguration
settings and can not easily be mocked in a sane way. They
are also not very helpfull and the functionality tested is
unlikly to break. They are removed for now.

Change-Id: Ic162e950d4df75e1b8aea63a6c547139efabdf15
Resolves: #57185
Related: #51436
Related: #57035
Releases: 6.2
Reviewed-on: https://review.typo3.org/28644
Reviewed-by: Christian Kuhn
Tested-by: Christian Kuhn
Reviewed-by: Helmut Hummel
Tested-by: Helmut Hummel