Remove mCached and mEmpty from PSR and calculate on query

The mCached and mEmpty are effectively descriptions of oomAdj and
ProcState. Calculating cached and empty states from oomAdj and procState
guarantees there will be no desync from those respective states.

Also cache adjType for Activity-based policies, so it does not get wiped
out by subsequent computes in an update.

Fixes: 302754011
Test: atest MockingOomAdjusterTests
Test: atest ServiceBindingOomAdjPolicyTest
Change-Id: Icc1f5a772a0739d28718f4e1255f1c33204b77a9