[BUGFIX] FormViewHelper creates inline styling

Due to accessibility reasons the inline styling of a container is
removed.

Change-Id: I8d3759ebac694a5a4254beb2f7d7561f6c73beaa
Fixes: #40826
Fluid Package Issue: #42743
Releases: 6.1, 6.0, 4.7, 1.3
Reviewed-on: https://review.typo3.org/18573
Reviewed-by: Wouter Wolters
Tested-by: Wouter Wolters
Reviewed-by: Alexander Schnitzler
Tested-by: Alexander Schnitzler