Deprecate IDreamManager startDozing and finishSelf

Their synchronous execution was a common source of severe jank so one-way versions startDozingOneway and finishSelfOneWay were provided as a removal.

Deprecated methods should be removed and Oneway renamed after the flag is cleaned up.

Bug: 330287187
Change-Id: If9987fbfcf2cc5e2bd613825f7e7034e9c2924a4
Flag: android.service.dreams.start_and_stop_dozing_in_background
Test: build