[TASK] Simplify chunking of test-plan jobs

To make the code for splitting all test-jobs into stages of equal size
simpler and easier to maintain, a helper class is introduced
that supports chunking two lists into equally sized chunks, while
ensuring that each chunk only contains a limited number of elements
from one of the lists.

Using this utility, the number of mssql jobs can easily be limited,
while keeping the spec-code easy to follow.

Releases: master, 9.5, 8.7
Resolves: #89948
Change-Id: I9e1677e19fb2ea6df7d9e964e8f772ffb7324ec8
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/62640


Tested-by: TYPO3com <noreply@typo3.com>
Tested-by: Andreas Fernandez <a.fernandez@scripting-base.de>
Tested-by: Anja Leichsenring <aleichsenring@ab-softlab.de>
Reviewed-by: Andreas Fernandez <a.fernandez@scripting-base.de>
Reviewed-by: Anja Leichsenring <aleichsenring@ab-softlab.de>