[BUGFIX] Use better icons for backend layout grid editor actions

Change-Id: Ie2ca536b5e1bd6e28e46af8073aaff4e298ddecf
Resolves: #85008
Releases: master, 8.7
Reviewed-on: https://review.typo3.org/56962


Tested-by: TYPO3com <no-reply@typo3.com>
Reviewed-by: Riccardo De Contardi <erredeco@gmail.com>
Tested-by: Riccardo De Contardi <erredeco@gmail.com>
Reviewed-by: Frank Naegler <frank.naegler@typo3.org>
Tested-by: Frank Naegler <frank.naegler@typo3.org>