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

This reverts commit ef71d61619d7da17131c38531308d4abbfa8dbf5

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: Iad674e88ea488d3bcee4d306b3e5c935a4c90334
Reviewed-on: https://review.typo3.org/22670
Reviewed-by: Anja Leichsenring
Tested-by: Anja Leichsenring