[BUGFIX] Use correct icon for mounting as tree root in context menu

The monochromatic icon is used instead of a red page type icon.

Resolves: #77733
Releases: master, 7.6
Change-Id: Iab959a5a3a9f5ac6f005de9ea23eef165cf4c45b
Reviewed-on: https://review.typo3.org/49703


Reviewed-by: Frans Saris <franssaris@gmail.com>
Tested-by: Frans Saris <franssaris@gmail.com>
Reviewed-by: Andreas Fernandez <typo3@scripting-base.de>
Tested-by: Andreas Fernandez <typo3@scripting-base.de>