Enrich not invoked in HttpClient instrumentation when HostNotFound

[alanwest]

While implementing an enrich function, I noticed that HTTP Socket Exceptions with the error code HostNotFound do not trigger the enrich function on exception because of these lines in HttpHandlerDiagnosticListener.

This prevents additional information from being captured in the activity when the exception is a HostNotFound Socket Exception.

Can someone shed some light on this particular behaviour? I could not find anything in the documentation.

Thank you.

Originally posted by @tl-amanda-oh in #3208