[TASK] travis-ci: Less parallel jobs

travis-ci still chockes on functional tests, even if
splitting them among lots of single tasks. Run less
tests in parallel and split to ever more jobs to have
a higher chance for 10 minute output with given cpu
constraints.

Change-Id: Iafc984aaef96ec59422f9c48a74b7308dd7cd7d7
Resolves: #82170
Releases: master, 8.7, 7.6
Reviewed-on: https://review.typo3.org/53779


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