Ensure NFW gets reported before result is reported to client and remove async listener in queue

[dibarbet]

Should resolve https://dev.azure.com/devdiv/DevDiv/_workitems/edit/2224584

Optprof web application tests have been failing for a while in VS. Tim tracked down the issue to an async listener introduced in #74530

The never completing listener were requests for workspace diagnostics. This is actually expected for workspace diagnostics requests, as they are held open indefinitely if nothing changes (see https://github.com/dotnet/roslyn/blob/main/src/LanguageServer/Protocol/Handler/Diagnostics/AbstractWorkspacePullDiagnosticsHandler.cs#L94). So as long as workspace diagnostics requests function this way, it is easy to get into a situation where there are async listeners that never complete.

The queue async listener was introduced to ensure that unit tests could reliably verify if the NFW handler was called (as handling the exception happened after the response was returned to the client).

To resolve this issue I did a couple things

1. Move reporting NFW for request exceptions into the telemetry reporting scope. Importantly this scope is called before the result is sent back to the client. This allows unit tests to simply wait for the request to complete before checking if the NFW handler was called (no need for an async listener).
2. Removing the async listener from the queue now that no unit tests need to wait for an action to occur in the queue.

TODO - validate optprof

[dibarbet]

passing optprof (internal only - https://devdiv.visualstudio.com/DevDiv/_build/results?buildId=10559193&view=results)