[TASK] Clean up acceptance tests

Merge the login related tests into one test case
and use the default \AcceptanceTester to do the tests.

Change-Id: I7e018fb1cdf10aada9854931736f87593ceeff10
Resolves: #76331
Releases: master
Reviewed-on: https://review.typo3.org/48340


Reviewed-by: Wouter Wolters <typo3@wouterwolters.nl>
Tested-by: Wouter Wolters <typo3@wouterwolters.nl>
Reviewed-by: Christian Kuhn <lolli@schwarzbu.ch>
Tested-by: Christian Kuhn <lolli@schwarzbu.ch>