Merge "SurfaceFlinger: add more cleanup to unittests"

        // still be referenced by something despite our best efforts to destroy

        // it after each test is done.

        mutableDisplays().clear();

        mutableCurrentState().displays.clear();

        mutableDrawingState().displays.clear();

        mutableEventQueue().reset();

        mutableInterceptor().reset();

        mutableScheduler().reset();