[BUGFIX] Avoid PHP notice in DataHandler

The fifth parameter to Datahandler::insertDB() is used in one place
without properly checking for the existence of the array element.
In general this parameter is only used for imp/exp extension
and works for admins only.

Resolves: #88025
Releases: master, 9.5
Change-Id: Iba5656857b1b16fb601a3c6af424a6477edc6956
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/60348


Tested-by: TYPO3com <noreply@typo3.com>
Tested-by: Anja Leichsenring <aleichsenring@ab-softlab.de>
Tested-by: Daniel Goerz <daniel.goerz@posteo.de>
Reviewed-by: Oliver Klee <typo3-coding@oliverklee.de>
Reviewed-by: Anja Leichsenring <aleichsenring@ab-softlab.de>
Reviewed-by: Daniel Goerz <daniel.goerz@posteo.de>