Revert "[BUGFIX] setRespectSysLanguage(FALSE) doesn't prevent language overlay"

This reverts commit c68b4b0d0d9ff1af00428ebef098c398f1c1f8a8

The patch introduces a regression. We have no easy fix for it, so the patch gets reverted. Sorry for now, we come back to the problem.

Change-Id: I04f92455cddd3f628144b5496a934904cb4ccd98
Reviewed-on: https://review.typo3.org/22672
Reviewed-by: Anja Leichsenring
Tested-by: Anja Leichsenring