am: Make OomAdjuster.evaluateConnectionPrelude to use internal classes

This change migrates the OomAdjusterImpl.evaluateConnectionPrelude()
method to access ProcessRecordInternal. This is a pure refactor to
align with internal class migration efforts and improve modularity.

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

Change-Id: I4ca546c58de21b0f7212f5d7a57e0eb041ba9ea4