[TASK] Avoid static DatabaseSnashot setup in functional tests

The testing-framework simplified database snapshotting.
Calling static initializeDatabaseSnapshot() and
tearDownAfterClass() are on longer needed.

composer req --dev typo3/testing-framework:^6.15.1

Change-Id: I0921d8c0c99d2dc677a607a0ba3eecbb1bf39763
Resolves: #96264
Releases: main, 11.5
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/72530


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