[TASK] Streamline DataHandler functional tests

Live and Workspaces share quite a lot of common test cases which however
are duplicated for each scenario. To ease the integration of new tests
for both scenarios, these superfluous redundancies are removed.

Resolves: #79833
Releases: master
Change-Id: I2ef2ee63d9c052ea5e9a5a8ddae7c63f15abf58d
Reviewed-on: https://review.typo3.org/51701


Tested-by: TYPO3com <no-reply@typo3.com>
Reviewed-by: Oliver Hader <oliver.hader@typo3.org>
Tested-by: Oliver Hader <oliver.hader@typo3.org>