[TASK] Remove leftover IMGMENU code

Remove leftover code of IMGMENU, which has been deprecated in v9 and removed in v10.

Resolves: #101979
Related: #101973
Related: #85902
Releases: main
Change-Id: I6c0f0df3065ab7b7cc3368d5ba383f0cd27645aa
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/81112


Tested-by: core-ci <typo3@b13.com>
Tested-by: Andreas Nedbal <andy@pixelde.su>
Reviewed-by: Benni Mack <benni@typo3.org>
Reviewed-by: Oliver Bartsch <bo@cedev.de>
Tested-by: Oliver Klee <typo3-coding@oliverklee.de>
Reviewed-by: Andreas Nedbal <andy@pixelde.su>
Tested-by: Oliver Bartsch <bo@cedev.de>
Tested-by: Benni Mack <benni@typo3.org>