am: Decouple ConnectionRecord with OomAdjuster

This change makes `ConnectionRecordInternal` implements the interface
`OomAdjusterImpl.Connection`.

Now the method `OomAdjuster.computeServiceHostOomAdjLSP` no longer uses
ConnectionRecord and switches to use `ConnectionRecordInternal`.

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

Change-Id: I9f724edd874436c8d6ca1b29fdff098c493a6da1