SummarizingChatReducer_Streaming test consistently failing. Omitting the initial user info

[ericstj]

I found this when testing the latest (with OpenAI 2.8.0) however I reverted that change and still reproduced. I was also able to repro with 10.1 and 10.0 so it's not a recent regression.

https://github.com/dotnet/extensions/blob/cc328a764d1b0200a852772b1f163ebecc7f4a22/test/Libraries/Microsoft.Extensions.AI.Integration.Tests/ChatClientIntegrationTests.cs#L1275-L1317

      Microsoft.Extensions.AI.OpenAIAssistantChatClientIntegrationTests.SummarizingChatReducer_Streaming (8s 326ms): Error Message: Assert.Collection() Failure: Item comparison failure
                   ↓ (pos 0)
      Collection: [Personalized learning can really enhance student engagement and outcomes. How do you implement that in your tools?, Personalized learning is the future of education!, Was anyone named in the conversation? Provide their name and job.]
      Error:      Assert.Contains() Failure: Sub-string not found
                  String:    "Personalized learning can really enhance "···
                  Not found: "Bob"
                  Stack Trace:
                    C:\src\dotnet\extensions\test\Libraries\Microsoft.Extensions.AI.Integration.Tests\ChatClientIntegrationTests.cs(1305,0): at Microsoft.Extensions.AI.ChatClientIntegrationTests.<>c.<SummarizingChatReducer_Streaming>b__66_0(ChatMessage m)
      Stack Trace:
         at Microsoft.Extensions.AI.ChatClientIntegrationTests.<SummarizingChatReducer_Streaming>d__66.MoveNext() in C:\src\dotnet\extensions\test\Libraries\Microsoft.Extensions.AI.Integration.Tests\ChatClientIntegrationTests.cs:line 1301
      --- End of stack trace from previous location where exception was thrown ---
         at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
         at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
      --- End of stack trace from previous location where exception was thrown ---
         at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
         at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
      --- End of stack trace from previous location where exception was thrown ---
         at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
         at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)