[BUGFIX] Workspace toolbar styling fix (UL)

When you open the workspace toolbar, the bullets
of the list are shown. It should not.

Resolves: #57114
Related: #55819
Releases: 6.2
Change-Id: Ia58ddd1cd8005d6e2410c04e28a2a7b2111665c4
Reviewed-on: https://review.typo3.org/28591
Reviewed-by: Ernesto Baschny
Tested-by: Ernesto Baschny
Reviewed-by: Wouter Wolters
Tested-by: Wouter Wolters