domain neutral instrumentation fails in 1.17.0

Describe the bug After upgrading from 1.16.2 to 1.17.0 per this issue, and re-enabling domain neutral instrumentaton, the tracing agent logs a warn: Method replacement found but the managed profiler has not yet been loaded into AppDomain and fails to capture traffic from domain neutral assemblies.

To Reproduce Steps to reproduce the behavior:

1. From .NET tracer version 1.16.2 Install 1.17.0
2. Add DD_TRACE_DOMAIN_NEUTRAL_INSTRUMENTATION as a System environment variable with value true
3. Restart machine

Expected behavior domain neutral assemblies are captured in DD trace views

Runtime environment (please complete the following information):

• Instrumentation mode: Automatic
• Tracer version: 1.17.0
• OS: Windows Server 2016 Datacenter
• CLR: .NET Framework 4.7.2

Additional context

• Was working fine in tracer version 1.16.2
• We only have 1 site per application pool.

[w3wp.exe] 7036: [info] Detected environment variable DD_TRACE_DOMAIN_NEUTRAL_INSTRUMENTATION=true
[w3wp.exe] 3636: [info] ModuleLoadFinished: Datadog.Trace.ClrProfiler.Managed.Loader loaded into AppDomain 341937672 /LM/W3SVC/1/ROOT/xxxxxxx-1-132345695907704549
[w3wp.exe] 4840: [info] JITCompilationStarted: Startup hook registered in function_id=361337040 token=100688380 name=System.Web.Compilation.BuildManager.InvokePreStartInitMethods(), assembly_name=System.Web app_domain_id=1937404912 domain_neutral=1
[w3wp.exe] 3636: [info] AssemblyLoadFinished: Datadog.Trace.ClrProfiler.Managed v1.17.0 matched profiler version v1.17.0
[w3wp.exe] 3636: [info] AssemblyLoadFinished: Datadog.Trace.ClrProfiler.Managed was not loaded domain-neutral
[w3wp.exe] 3636: [warn] JITCompilationStarted skipping method: Method replacement found but the managed profiler has not yet been loaded into AppDomain with id=1937404912 function_id=648750164 token=100665474 caller_name=System.Data.Linq.SqlClient.SqlProvider.Execute() target_name=System.Data.Common.DbCommand.ExecuteReader()
[w3wp.exe] 3636: [warn] JITCompilationStarted skipping method: Method replacement found but the managed profiler has not yet been loaded into AppDomain with id=1937404912 function_id=648750164 token=100665474 caller_name=System.Data.Linq.SqlClient.SqlProvider.Execute() target_name=System.Data.Common.DbCommand.ExecuteReader()
[w3wp.exe] 3636: [warn] JITCompilationStarted skipping method: Method replacement found but the managed profiler has not yet been loaded into AppDomain with id=1937404912 function_id=648750164 token=100665474 caller_name=System.Data.Linq.SqlClient.SqlProvider.Execute() target_name=System.Data.Common.DbCommand.ExecuteReader()
[w3wp.exe] 3636: [warn] JITCompilationStarted skipping method: Method replacement found but the managed profiler has not yet been loaded into AppDomain with id=1937404912 function_id=648750164 token=100665474 caller_name=System.Data.Linq.SqlClient.SqlProvider.Execute() target_name=System.Data.Common.DbCommand.ExecuteNonQuery()

[scownTownV]

@lucaspimentel do you have an ETA on the next release date?

[lucaspimentel]

@scownTownV: We recently found out that the flag DD_TRACE_DOMAIN_NEUTRAL_INSTRUMENTATION did not cover all intended cases. The fix (#738) should be ready for the next tracer release.