[CLEANUP] Remove initialization of Module Menu

The module menu and its view are instantiated
on every backend call, BE AJAX call etc although
it is only needed in the backend.php file where
it instantiates itself automatically anyways.

The patch removes the call in init.php and
in the TYPO3 Bootstrap as it is not needed
anymore.

Releases: 6.2
Resolves: #55565
Change-Id: I67b6fb54380485d35c070867abf67e3ed416f004
Reviewed-on: https://review.typo3.org/27242
Reviewed-by: Marcin Sągol
Tested-by: Marcin Sągol
Reviewed-by: Stefan Neufeind
Tested-by: Stefan Neufeind