Cleanup dead delegate code

[MichalPetryka]

Split off from #99200

cc @jkotas

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[MichalPetryka]

@jkotas Can you review this next so that I can rebase #99200?

[jkotas]

The diagnostic tests are failing with number of errors. Example of failure:

System.InvalidOperationException : Field not found in any layout (names=[InvocationList]).

   at Microsoft.Diagnostics.DataContractReader.Generated.LayoutSet.Select(TargetPointer address, TypeInfo& type, TargetPointer& baseAddr, String& name, ReadOnlySpan`1 names) in /_/artifacts/obj/Microsoft.Diagnostics.DataContractReader.Contracts/Debug/Microsoft.Diagnostics.DataContractReader.DataGenerator/Microsoft.Diagnostics.DataContractReader.DataGenerator.CdacGenerator/LayoutSet.g.cs:line 60
   at Microsoft.Diagnostics.DataContractReader.Data.Delegate..ctor(Target target, TargetPointer address) in /_/artifacts/obj/Microsoft.Diagnostics.DataContractReader.Contracts/Debug/Microsoft.Diagnostics.DataContractReader.DataGenerator/Microsoft.Diagnostics.DataContractReader.DataGenerator.CdacGenerator/Microsoft_Diagnostics_DataContractReader_Data.Delegate.g.cs:line 38
   at Microsoft.Diagnostics.DataContractReader.Data.Delegate.Microsoft.Diagnostics.DataContractReader.Data.IData<Microsoft.Diagnostics.DataContractReader.Data.Delegate>.Create(Target target, TargetPointer address) in /_/artifacts/obj/Microsoft.Diagnostics.DataContractReader.Contracts/Debug/Microsoft.Diagnostics.DataContractReader.DataGenerator/Microsoft.Diagnostics.DataContractReader.DataGenerator.CdacGenerator/Microsoft_Diagnostics_DataContractReader_Data.Delegate.g.cs:line 50
   at Microsoft.Diagnostics.DataContractReader.TestInfrastructure.TestPlaceholderTarget.DefaultDataCache.GetOrAdd[T](TargetPointer address) in /_/src/native/managed/cdac/tests/TestInfrastructure/TestPlaceholderTarget.cs:line 570
   at Microsoft.Diagnostics.DataContractReader.Contracts.Object_1.GetDelegateInfo(TargetPointer address) in /_/src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Contracts/Object_1.cs:line 164
   at Microsoft.Diagnostics.DataContractReader.Tests.ObjectTests.GetDelegateInfo_Multicast(Architecture arch) in /_/src/native/managed/cdac/tests/UnitTests/ObjectTests.cs:line 445
   at InvokeStub_ObjectTests.GetDelegateInfo_Multicast(Object, Span`1)
   at System.Reflection.MethodBaseInvoker.InvokeWithOneArg(Object obj, BindingFlags invokeAttr, Binder binder, Object[] parameters, CultureInfo culture)

[MichalPetryka]

The diagnostic tests are failing with number of errors. Example of failure:

System.InvalidOperationException : Field not found in any layout (names=[InvocationList]).

   at Microsoft.Diagnostics.DataContractReader.Generated.LayoutSet.Select(TargetPointer address, TypeInfo& type, TargetPointer& baseAddr, String& name, ReadOnlySpan`1 names) in /_/artifacts/obj/Microsoft.Diagnostics.DataContractReader.Contracts/Debug/Microsoft.Diagnostics.DataContractReader.DataGenerator/Microsoft.Diagnostics.DataContractReader.DataGenerator.CdacGenerator/LayoutSet.g.cs:line 60
   at Microsoft.Diagnostics.DataContractReader.Data.Delegate..ctor(Target target, TargetPointer address) in /_/artifacts/obj/Microsoft.Diagnostics.DataContractReader.Contracts/Debug/Microsoft.Diagnostics.DataContractReader.DataGenerator/Microsoft.Diagnostics.DataContractReader.DataGenerator.CdacGenerator/Microsoft_Diagnostics_DataContractReader_Data.Delegate.g.cs:line 38
   at Microsoft.Diagnostics.DataContractReader.Data.Delegate.Microsoft.Diagnostics.DataContractReader.Data.IData<Microsoft.Diagnostics.DataContractReader.Data.Delegate>.Create(Target target, TargetPointer address) in /_/artifacts/obj/Microsoft.Diagnostics.DataContractReader.Contracts/Debug/Microsoft.Diagnostics.DataContractReader.DataGenerator/Microsoft.Diagnostics.DataContractReader.DataGenerator.CdacGenerator/Microsoft_Diagnostics_DataContractReader_Data.Delegate.g.cs:line 50
   at Microsoft.Diagnostics.DataContractReader.TestInfrastructure.TestPlaceholderTarget.DefaultDataCache.GetOrAdd[T](TargetPointer address) in /_/src/native/managed/cdac/tests/TestInfrastructure/TestPlaceholderTarget.cs:line 570
   at Microsoft.Diagnostics.DataContractReader.Contracts.Object_1.GetDelegateInfo(TargetPointer address) in /_/src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Contracts/Object_1.cs:line 164
   at Microsoft.Diagnostics.DataContractReader.Tests.ObjectTests.GetDelegateInfo_Multicast(Architecture arch) in /_/src/native/managed/cdac/tests/UnitTests/ObjectTests.cs:line 445
   at InvokeStub_ObjectTests.GetDelegateInfo_Multicast(Object, Span`1)
   at System.Reflection.MethodBaseInvoker.InvokeWithOneArg(Object obj, BindingFlags invokeAttr, Binder binder, Object[] parameters, CultureInfo culture)

Could somebody from cdac team assist here? I'm not sure how to get the multicast fields properly.

[MichalPetryka]

@jkotas does it look good now?

[jkotas]

Thank you!