`Yarp.ReverseProxy.DistributedTracingTests.DistributedTracing_Works` test case fails on branch main

[Xulei-NL]

Describe the bug

The Yarp.ReverseProxy.DistributedTracingTests.DistributedTracing_Works test case fails with the lastest main branch code. In my opinion the main branch's test cases should all be passed by defaul.

Looking forward to your comments.

To Reproduce

1. Clone the Yarp code: git clone https://github.com/dotnet/yarp.git.
2. Build Yarp: zsh build.sh.
3. Run test case: zsh build.sh -test.

Then I saw the error message:

Yarp.ReverseProxy.FunctionalTests failed with 1 error(s) (23.5s)
    XUnit : error Tests failed: /private/tmp/yarp/artifacts/TestResults/Debug/Yarp.ReverseProxy.FunctionalTests_net8.0_x64.html [net8.0|x64]

Further technical details

• The platform: macOS M4Max
• Failed test case detail, also attached Yarp.ReverseProxy.FunctionalTests_net8.0_x64.html:

Yarp.ReverseProxy.DistributedTracingTests.DistributedTracing_Works(idFormat: Hierarchical)
Assert.StartsWith() Failure: String start does not match
String:         \"\"
Expected start: \"|ca4bd19f-4f6af408a6d1b029.\"
   at Yarp.ReverseProxy.DistributedTracingTests.ValidateActivities(ActivityIdFormat idFormat, Activity client, HeaderDictionary proxy, HeaderDictionary downstream) in /private/tmp/yarp/test/ReverseProxy.FunctionalTests/DistributedTracingTests.cs:line 97
   at Yarp.ReverseProxy.DistributedTracingTests.DistributedTracing_Works(ActivityIdFormat idFormat) in /private/tmp/yarp/test/ReverseProxy.FunctionalTests/DistributedTracingTests.cs:line 70
--- End of stack trace from previous location ---

[MihaZupan]

This is a test-only issue as described in #3023