[TASK] Prepare TYPO3 tests to use phpunit v9

Remove usage of $mock->at() matcher and some other
deprecated matchers.

Following matchers are deprecated in phpunit v9:

* at()
* assertRegExp()
* assertFileNotExists()

Those were replaced with their respective replacements.

Resolves: #92461
Releases: master, 10.4
Change-Id: Id8373659160c219c2caff8bcbe0bdb9b0da16436
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/65971


Tested-by: TYPO3com <noreply@typo3.com>
Tested-by: Christian Kuhn <lolli@schwarzbu.ch>
Tested-by: Oliver Bartsch <bo@cedev.de>
Tested-by: Anja Leichsenring <aleichsenring@ab-softlab.de>
Reviewed-by: Christian Kuhn <lolli@schwarzbu.ch>
Reviewed-by: Oliver Bartsch <bo@cedev.de>
Reviewed-by: Anja Leichsenring <aleichsenring@ab-softlab.de>