[TASK] Remove not needed icons & css

Resolves: #49638
Releases: 6.2
Change-Id: I6ddba64d386f8c0d7d209124c255875585c16d2b
Reviewed-on: https://review.typo3.org/21846
Reviewed-by: Christian Kuhn
Tested-by: Christian Kuhn
Reviewed-by: Georg Ringer
Tested-by: Georg Ringer