Remove hover highlight before opening view context menu

If one was fast to open the right-click context menu on the row of
an item in details view mode, the hover highlight would persist
while the context menu for the view was open.

This one-liner makes it so the highlight on the row is always
removed before the right-click context menu for the view is opened
so it is as clear as possible that the newly opened context menu
has no relation to the fileItem.