psc: Use ProcessRecordInternal for specific OomAdjuster states

Updates the OomAdjuster's GlobalState interface and related methods
to use ProcessRecordInternal instead of ProcessRecord for Home,
HeavyWeight, and Previous processes.

Bug: 425766486
Test: m services.core
Flag: EXEMPT pure refactor

Change-Id: Ic089a81ce54fafc7833977a67ed6af7552a0edc1