Migrate to system interface getSystemCarDir() for saved config.

System interface provides a dir that is not constrained by unlocking
user, so we no longer need to listen to system event broadcast.

Fix: 124460962
Test: atest CarServiceTest:CarUxRestrictionsManagerServiceTest
Test: verified on mojave

Change-Id: I445b655a9655bd3d454650e68fb3e5d6c06e9f09
diff --git a/service/src/com/android/car/ICarImpl.java b/service/src/com/android/car/ICarImpl.java
index d81285a..034a881 100644
--- a/service/src/com/android/car/ICarImpl.java
+++ b/service/src/com/android/car/ICarImpl.java
@@ -123,7 +123,7 @@
         mCarPropertyService = new CarPropertyService(serviceContext, mHal.getPropertyHal());
         mCarDrivingStateService = new CarDrivingStateService(serviceContext, mCarPropertyService);
         mCarUXRestrictionsService = new CarUxRestrictionsManagerService(serviceContext,
-                mCarDrivingStateService, mCarPropertyService, mUserManagerHelper);
+                mCarDrivingStateService, mCarPropertyService);
         mCarPackageManagerService = new CarPackageManagerService(serviceContext,
                 mCarUXRestrictionsService,
                 mSystemActivityMonitoringService);