[BUGFIX] Remove additional lines in textareas of formengine

Remove additional lines around the actual content of a
textarea.

Resolves: #79573
Releases: master
Change-Id: I636afb0ec63d34d4a209caeaa1369bc65727665d
Reviewed-on: https://review.typo3.org/51490


Reviewed-by: Markus Klein <markus.klein@typo3.org>
Tested-by: Markus Klein <markus.klein@typo3.org>
Tested-by: TYPO3com <no-reply@typo3.com>
Reviewed-by: Thomas Hohn <thomas@hohn.dk>
Reviewed-by: Jigal van Hemert <jigal.van.hemert@typo3.org>
Tested-by: Jigal van Hemert <jigal.van.hemert@typo3.org>