Do not filter routes on privileged RoutingControllers

With this change, privileged RoutingControllers will stop filtering
routes by feature when providing selected, selectable, and deselectable
routes, which should unify the behaviour between regular and privileged
controllers.

Test: atest MediaRouter2Test SystemMediaRouter2Test
Bug: 289910189
Change-Id: Iae6fa3785ed79f6a8e78618868a21c472387604a