Fix UserSwitchTransitionViewMediatorTest

First, it has to extend SystemUiTestCase to pass AAAPlusPlusVerify Test.
Second, CarDeviceProvisionedController is injected into the Mediator and
mocked in its test to correctly test case where the user life cycle
event is being applied to the current user and a case when it is not.

Bug: 161892451
Test: Unit Test (the corresponding tests passing now.)
Change-Id: I8be7dacaa1bf0abb87dcb357c37e58ce511132d2