[BUGFIX] Return an OK message if permissions are already fine

If the permissions are already ok, better return an OK FlashMessage
instead of throwing an exception.

Resolves: #103728
Releases: main, 12.4
Change-Id: I280b1de894dcb78bc222ff1f585ff37627408e5c
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/84575


Reviewed-by: Jasmina Ließmann <minapokhalo+typo3@gmail.com>
Tested-by: Jasmina Ließmann <minapokhalo+typo3@gmail.com>
Tested-by: Christian Kuhn <lolli@schwarzbu.ch>
Reviewed-by: Christian Kuhn <lolli@schwarzbu.ch>
Tested-by: core-ci <typo3@b13.com>