Remove AppDomain parameter for Debugger::InitIPCEvent

[elinor-fung]

Follow-up from #101749 (comment)
Always the one and only AppDomain.

cc @dotnet/dotnet-diag @AaronRobinsonMSFT

[Copilot]

Pull Request Overview

This PR simplifies IPC event initialization by removing the AppDomain parameter from Debugger::InitIPCEvent and always using the current AppDomain internally.

• Deleted the four-parameter overload in the header.
• Updated all callers in debugger.cpp to use the three-parameter variant.
• Inlined VMPTR_AppDomain::MakePtr(AppDomain::GetCurrentDomain()) inside the implementation.

Reviewed Changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.

File	Description
src/coreclr/debug/ee/debugger.h	Removed the overload that accepted an AppDomain*.
src/coreclr/debug/ee/debugger.cpp	Updated all InitIPCEvent calls to the new signature and defaulted the domain internally.

Comments suppressed due to low confidence (2)

src/coreclr/debug/ee/debugger.cpp:2791

• Consider adding or updating unit tests to verify that vmAppDomain is correctly set for all IPC events, especially those that previously used NullPtr, to ensure the new default behavior is as intended.

    );

src/coreclr/debug/ee/debugger.h:2768

• [nitpick] Update or add a comment here to explain that the AppDomain is now always the current domain and no longer needs to be passed in.

                      Thread *pThread)

[AaronRobinsonMSFT]

LGTM

/cc @dotnet/dotnet-diag

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[steveisok]

LGTM

[noahfalk]

It looks like there are places which are switching from NULL to GetCurrentAppDomain() which probably doesn't matter but there is a low chance it breaks something. If you haven't yet, can you test some basic debugging in Visual Studio like set a breakpoint in HelloWorld, hit it, and look at the locals?

[elinor-fung]

I checked that basic debugging worked (helloworld, breakpoint, locals, eval in watch window). Also scanned through some of the reading of the IPC events and didn't see NULL obviously having some special meaning.