am: Make forEachClientConnectionLSP use internal classes

This change migrates the OomAdjusterImpl.forEachClientConnectionLSP()
method to access psc internal record classes. 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: I97306978082fab545b667985454486eac5dac695