[TASK] Avoid dynamic property declaration

With PHP 8.2, dynamically declared properties raise a
deprecation warning, leading to test fails. Resolve these.

Resolves: #97969
Releases: main, 11.5
Change-Id: Idb1ad46415fcfa2c2c562863004c9f2b88cff58c
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/75216


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