[TASK] Fix casing of DropDownDivider class name

Use `DropDownDivider::class` instead of `DropdownDivider`.

Resolves: #100192
Releases: main
Change-Id: I5521fd87b3df8aa25f66208d78715e0b73bb8c09
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/78143


Reviewed-by: Oliver Klee <typo3-coding@oliverklee.de>
Tested-by: Josef Glatz <typo3@josefglatz.at>
Tested-by: Benni Mack <benni@typo3.org>
Reviewed-by: Josef Glatz <typo3@josefglatz.at>
Tested-by: core-ci <typo3@b13.com>
Reviewed-by: Benni Mack <benni@typo3.org>
Tested-by: Oliver Klee <typo3-coding@oliverklee.de>
Tested-by: Stefan Froemken <froemken@gmail.com>
Reviewed-by: Stefan Froemken <froemken@gmail.com>