No spans from blog trigger in isolated worker (host or worker)

[lmolkova]

Here's the repro app: https://github.com/lmolkova/testfuncotel

Environment:

• A .NET 9 RC 2 SDK
• Microsoft.Azure.Functions.Worker.Extensions.Http.AspNetCore at v2.0.0-preview1
• Microsoft.Azure.Functions.Worker.Sdk at v2.0.0-preview1
• Azure Functions Core Tools at v4.0.6280

It has:

• HTTP and blob triggers
• configures otel to collect incoming and outgoing HTTP and function worker sources
• it sends some custom spans from function invocations
• it exports all logs, traces and spans to local aspire dashboard

What I see:

• HTTP trigger works fine: spans and logs are exported as expected
  

• Blob trigger does not produce any spans from the worker - even custom ones. It produces a bunch spans from the host, but none of them are related to the specific invocation (or not correlated to it)

• It produces logs, which have trace-id, but there is no corresponding trace
  

  Mysteriously, even the custom activity that works perfectly fine in the HTTP trigger becomes null inside blob trigger.

  It also produces a bunch of host-level storage-polling noise, but I don't see any spans describing the triggered function
  

Expected:

Blob trigger is reported as a span on the host and custom activity is reported from inside the trigger code.