Revert "Replace CordbProcess::GetSharedDomain with GetAppDomain"

[davidwrighton]

Reverts #117037 This breaks debugging basics.

Notably, enumerating the list of assemblies results in an infinite loop as it builds more and more CorDbAssembly objects.

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[Copilot]

Pull Request Overview

Reverts previous PR (#117037) that replaced thread-specific domain lookup with a single-domain model, restoring per-thread GetCurrentAppDomain behavior and introducing a shared default AppDomain fallback.

• Updated IDacDbiInterface and its implementation to take a vmThread parameter for GetCurrentAppDomain.
• Modified all callers in CordbThread, CordbProcess, and related classes to pass their thread token.
• Added GetSharedAppDomain, m_sharedAppDomain fallback, and UpdateThreadsForAdUnload to manage default domain unloading and thread cleanup.

Reviewed Changes

Copilot reviewed 8 out of 8 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
src/coreclr/debug/inc/dacdbiinterface.h	Changed GetCurrentAppDomain to accept a vmThread argument.
src/coreclr/debug/di/rsthread.cpp	Updated calls to GetCurrentAppDomain with vmThread.
src/coreclr/debug/di/rspriv.h	Adjusted CacheAssembly overload signatures; renamed GetAppDomain.
src/coreclr/debug/di/rsappdomain.cpp	Refactored assembly caching/removal to use VMPTR_DomainAssembly.
src/coreclr/debug/di/process.cpp	Added m_sharedAppDomain, GetSharedAppDomain, and thread cleanup.
src/coreclr/debug/di/module.cpp	Fallback to GetSharedAppDomain when no DomainAssembly is available.
src/coreclr/debug/daccess/dacdbiimpl.h/.cpp	Added thread-parameter overload for GetCurrentAppDomain.

[elinor-fung]

Thanks. I only tried VS and SOS unit tests as basic testing, which apparently don't go down the broken path. Clearly needed windbg too.

[elinor-fung]

#117221 is the fix for assemblies not being found in the cache. Assuming this goes in first, I'll update that to be the revert of the revert.