[BUGFIX] Fix test isolation and pre-requisites

FormDefinitionValidationServiceTest modified the encryption key in
test data-provider functions. Those functions are executed prior to
actually executing the tests and causes side-effects during running
the test suite.

Resolves: #85539
Releases: master, 9.3, 8.7
Change-Id: I9fbd60905eb37470fa3661225b681476ff9df3c3
Reviewed-on: https://review.typo3.org/57570


Reviewed-by: Christian Kuhn <lolli@schwarzbu.ch>
Tested-by: Christian Kuhn <lolli@schwarzbu.ch>
Tested-by: TYPO3com <no-reply@typo3.com>
Reviewed-by: Oliver Hader <oliver.hader@typo3.org>
Tested-by: Oliver Hader <oliver.hader@typo3.org>