Restore the default power policy after test

Device's components could be in power off state if the default power
policy is not restored after CarPowerManagerTest.

Bug: 193718474
Test: 1. atest CtsCarTestCases:CarPowerManagerTest
      2. check if Wifi is enabled in the setting UI
      3. use adb shell dumpsys car_service --services
      CarPowerManagementService to check current power policy id is
      system_power_policy_all_on
      4. run the test over Seahawk, emulator and cf
Change-Id: I9c55b64f0bba6b0d5ff87b709fc714ff9ffc704c
1 file changed