[TASK] Remove superflous require_once in t3editor hook

\TYPO3\CMS\T3editor\Hook\FileEditHook::save() requires
init.php which is not necessary at all as the method
itself is only called through ajax.php, which requires
init.php itself anyway.

Resolves: #55676
Releases: 6.2
Change-Id: Iaaf0805b73ebbb97e6689bcaa8064dc350187e66
Reviewed-on: https://review.typo3.org/27848
Reviewed-by: Wouter Wolters
Tested-by: Wouter Wolters
Reviewed-by: Oliver Klee
Reviewed-by: Helmut Hummel
Tested-by: Helmut Hummel