Revert "[BUGFIX] Check for incompatible SQL modes"

The sysenv-check is not the proper place for a check that needs a working db-connection. But we'll find a different place for this check shortly and then reintroduce it.

This reverts commit bad3f24c1d106ce4d2254c1a8e5710edb769151e

Change-Id: I1ba4a2ed88ad03df122593ac964d997ec05edacf
Reviewed-on: https://review.typo3.org/23243
Reviewed-by: Stefan Neufeind
Tested-by: Stefan Neufeind