Fix CarPowerManagenentService crash in car service test

- add ICarImpl.asserCallingFromSystemProcessOrSelf() to prevent
  throwing exception when running car service code in car service
  unit testing.

Bug: 131928300
Test: Run car service tests, atest CarServiceTest

Change-Id: I68ce1978b3f5696cc643f44c00c0d94a760808c0
2 files changed