[BUGFIX] Acceptance test for extension manager

Now the extension recycler is used for testing instead of beuser.

Resolves: #78185
Related: #77820
Releases: master
Change-Id: If6b049861335fee6762082b40217acb355c649d1
Reviewed-on: https://review.typo3.org/50114


Tested-by: TYPO3com <no-reply@typo3.com>
Reviewed-by: Marc von Schalscha <msa@starfinanz.de>
Reviewed-by: Martin Fox <kontakt@mlis.pl>
Tested-by: Martin Fox <kontakt@mlis.pl>
Reviewed-by: Christian Kuhn <lolli@schwarzbu.ch>
Tested-by: Christian Kuhn <lolli@schwarzbu.ch>