Partially revert "Make Light Doze timings deterministic."

This partially reverts commit 1256b08b
to return to S behavior. We still retain the removal of one intermediate
state that wasn't fully necessary to the light dozing flow.

Reason for revert: b/243380086

Using an "implicit" light Doze means other parts of the system never
stop work and other app behaviors they otherwise would have if
the DeviceIdleController had explicitly entered light Doze.
Thus, using an "implicit" light Doze state to avoid a wakeup alarm
actually ends up potentially increasing battery drain.

Test: atest DeviceIdleTest
Test: atest FrameworksMockingServicesTests:DeviceIdleControllerTest
Change-Id: Ia976b1df6de091755b5b755424e44fb392a61ee5