[BUGFIX] Remove only 'CType' keys from wizard

Check for key name of 'CType' before removing the content
element from new content wizard.

This is a regression from #23864 where a hardcoded
CType column check was removed that is actually required
in this case.

Resolves: #61114
Related: #23864
Releases: master
Change-Id: Ib65410dee4f7328a3b8bbceaa21c8367843905f3
Reviewed-on: http://review.typo3.org/36418


Reviewed-by: Christian Kuhn <lolli@schwarzbu.ch>
Tested-by: Christian Kuhn <lolli@schwarzbu.ch>
Reviewed-by: Zbigniew Jacko <z.jacko@macopedia.pl>
Tested-by: Zbigniew Jacko <z.jacko@macopedia.pl>
Reviewed-by: Anja Leichsenring <aleichsenring@ab-softlab.de>
Tested-by: Anja Leichsenring <aleichsenring@ab-softlab.de>