[BUGFIX] EXT: setup — Increase Spacing

User configure their personal TYPO3 backend in EXT: setup.
Here loads of options feel at home.

To lead users when searching for options space is essential.
This patch brings vertical spacing to the formular rows.

Change-Id: I622ed5050eee14e7a653b0e41203126ebe898bb1
Resolves: #48388
Releases: 6.2
Reviewed-on: https://review.typo3.org/20925
Reviewed-by: Philipp Gampe
Tested-by: Philipp Gampe
Reviewed-by: Thomas Maroschik
Tested-by: Thomas Maroschik
Reviewed-by: Felix Kopp
Tested-by: Felix Kopp