[TASK] Update to PHPStan 1.9.4

The new version finds some more potential problems.

> composer req --dev phpstan/phpstan:^1.9.4
> composer req --dev phpstan/phpstan-phpunit:^1.3.2
> ./Build/Scripts/runTests.sh -s phpstanGenerateBaseline

Change-Id: Iae41030660fc24f8e5d83546cb9e22835517a719
Resolves: #99389
Releases: main, 11.5
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/77212


Tested-by: Benni Mack <benni@typo3.org>
Tested-by: core-ci <typo3@b13.com>
Reviewed-by: Benni Mack <benni@typo3.org>