[TASK] Disable ac tests in travis

Acceptance test are currently too flaky to be of
any use. To not hide currently more important stuff
like unit and functional tests, ac tests are disabled
until a higher stability can be reached.

Change-Id: Ifd0892a85aa3c1ffaea6f469e45f2168035d9771
Resolves: #75815
Releases: master
Reviewed-on: https://review.typo3.org/47808


Reviewed-by: Christian Kuhn <lolli@schwarzbu.ch>
Tested-by: Christian Kuhn <lolli@schwarzbu.ch>