Wear doze -> on transition

1. Don't disable auto-brightness when there's an offload brightness - when we have an offload brightness, we're waiting for a lux sample and we should use one as soon as we have it.

2. Offload brightness should only be used if auto-brightness is enabled (just in case).

3. Don't clear the offload brightness when stopping the offload session - after the session is stopped, if we don't have a lux sample yet, we need to continue to use the offload brightness.

4. The automatic strategy should have a higher priority than the offload strategy - as soon as we have a lux sample, we should use automatic brightness and stop using the offload brightness.

Bug: 327390922
Test: adb shell dumpsys display | grep -i "brightnessEvent"
Test: atest AutomaticBrightnessStrategyTest
Test: atest DisplayBrightnessControllerTest
Test: atest DisplayBrightnessStrategySelectorTest
Test: atest DisplayOffloadSessionImplTest
Test: atest DisplayPowerControllerTest
Change-Id: I541087382c82db877517db07aec3b7ea65ef0abb