[BUGFIX] Avoid double escaping in content element wizard

Fluid escapes the header already, therfore there is no
need to do it before in the controller.

Resolves: #80288
Releases: master
Change-Id: I7f16fb2aa1319cdfbc3a8c9226a86e98a8e8457a
Reviewed-on: https://review.typo3.org/52147


Tested-by: TYPO3com <no-reply@typo3.com>
Reviewed-by: Wouter Wolters <typo3@wouterwolters.nl>
Tested-by: Wouter Wolters <typo3@wouterwolters.nl>
Reviewed-by: Andreas Fernandez <typo3@scripting-base.de>
Reviewed-by: Christian Kuhn <lolli@schwarzbu.ch>
Tested-by: Christian Kuhn <lolli@schwarzbu.ch>