[BUGFIX] Remove wrong escaping of email sender

Remove a wrong escaping method from sysext form which causes email
problems.

Resolves: #60437
Releases: master, 6.2
Change-Id: I3a5447b55f4f0723637c04929de0412a4a3b67a7
Reviewed-on: http://review.typo3.org/33603
Reviewed-by: Markus Klein <klein.t3@reelworx.at>
Tested-by: Markus Klein <klein.t3@reelworx.at>