[BUGFIX] Added missing TCEforms palette-header padding

With the cleanup of the backend styles a padding of the
pallete header got missing.

This patch adds this padding just like the other headers
in the TCEforms.

Resolves: #59160
Releases: 6.2
Change-Id: I25ca0ccb0bbd7f4f6d014e12f1cebe1b12050718
Reviewed-on: https://review.typo3.org/30458
Reviewed-by: Georg Ringer
Tested-by: Georg Ringer