[TASK] Remove unused variable $dbType in DataHandler

Resolves: #98234
Related: #97462
Releases: main
Change-Id: I415b289ce4cb889e5b6fb85e9fb0746aac771865
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/75593


Tested-by: core-ci <typo3@b13.com>
Tested-by: Stefan Bürk <stefan@buerk.tech>
Tested-by: Nikita Hovratov <nikita.h@live.de>
Reviewed-by: Oliver Klee <typo3-coding@oliverklee.de>
Reviewed-by: Stefan Bürk <stefan@buerk.tech>
Reviewed-by: Nikita Hovratov <nikita.h@live.de>