SystemServer: spawn hwbinder threads before BatteryService

BatteryService is the first service that uses a hwbinder
call, so we need to spawn the threads for BatteryService to receive
callbacks prior to starting BatteryService.

Test: boot test
Test: manually sleep in SensorDeviceUtils, still boots

Bug: 68765551
Bug: 68217725

Change-Id: Iadd88897d4cf9e0e37af706452c15318115f2149