[TASK] Acceptance tests: chrome headless

Switch to chrome headless for acceptance tests. We
don't need xvfb and friends on bamboo anymore which
will be updated with another patch later.

Change-Id: Ieb78d3d198f7dd9dc882041d86b403099e0854c6
Resolves: #82659
Releases: master, 8.7
Reviewed-on: https://review.typo3.org/54272


Tested-by: TYPO3com <no-reply@typo3.com>
Reviewed-by: Christian Kuhn <lolli@schwarzbu.ch>
Tested-by: Christian Kuhn <lolli@schwarzbu.ch>