psc: Move hasAboveClient to ProcessRecordInternal

This change refactors `OomAdjuster.setIntermediateAdjLSP` to use
`ProcessRecordInternal` instead of `ProcessRecord`.

To support this, `hasAboveClient()` is introduced as an abstract
method in `ProcessRecordInternal`, with `ProcessRecord` overriding it
to delegate to `ProcessServiceRecord`'s `hasAboveClient()`.
This is a temporary measure for ongoing refactoring.

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

Change-Id: I1dc3353005776a36a341d0fb5384ffb31707df66