[TASK] Enable functionals with phpunit 10 in parallel to 9

This is a temporary, a bit hacky solution to
run the functional tests with phpunit 10 next
to phpunit 9 for now. Goal is to ensure they
don't break again.

We'll later remove phpunit 9, but need to still
sort out some further details.

Resolves: #100490
Related: #100249
Releases: main
Change-Id: I2b0d2b6abfec9236bc2f3f819b080338111b21ff
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/78495


Tested-by: Oliver Klee <typo3-coding@oliverklee.de>
Tested-by: core-ci <typo3@b13.com>
Reviewed-by: Stefan Bürk <stefan@buerk.tech>
Reviewed-by: Christian Kuhn <lolli@schwarzbu.ch>
Tested-by: Stefan Bürk <stefan@buerk.tech>
Tested-by: Christian Kuhn <lolli@schwarzbu.ch>