psc: Introduce ProcessServiceRecordInternal

This change moves service-related process state fields from
ProcessServiceRecord to a new abstract base class,
ProcessServiceRecordInternal. This encapsulates these internal state
variables and their accessors, improving modularity and preparing for
future PSC-related refactor.

Bug: 425766486
Test: m services.core
Test: atest MockingOomAdjusterTests OomAdjusterTests
Test: atest FrameworksServicesTestsRavenwood_ProcessStateController
Flag: EXEMPT pure refactor

Change-Id: I2a416ad2ea7f29b9f52983b734984e307a1fb267