[BUGFIX] Recycler ignores depth setting

The recycler currently ignores the depth
setting, because of a wrong type check
since the migration to mysqli.

Fixes: #48997
Releases: 6.2, 6.1
Change-Id: Ib7a4eb1fc68468ce09944bb9342e070a6ab3860f
Reviewed-on: https://review.typo3.org/21321
Reviewed-by: Wouter Wolters
Reviewed-by: Alexander Opitz
Tested-by: Alexander Opitz
Reviewed-by: Stefan Neufeind
Tested-by: Stefan Neufeind