Undo the jobscheduler / device idle initialization with callbacks

We'll be able to expose system APIs from jobscheduler-framework.jar and
use them from framework-minus-apex.jar, so these elaborated initialization
will not be needed.

Bug: 142281756
Test: boot, "dumpsys batterstats"
Change-Id: I957642fc2573818d138450747e0690d7176636ad