Fix Stream DeliveryMode

[sw-joelmut]

Description

This PR fixes an issue with the Stream DeliveryMode not being set correctly when the Agent1 sent a message to Agent2 using the Streamed functionality.

Detailed Changes

• Send the correctly activity clone that sets the delivery mode to Stream.

Testing

The following image shows the Agent1 and Agent2 working.

[Copilot]

Pull Request Overview

This PR corrects the delivery mode of streamed activities by passing the cloned activity into the streaming method rather than the original.

• Ensure the cloned activity (with DeliveryMode.Stream) is used in the inner streaming call.
• Prevents the bug where the original activity was sent without the proper delivery mode.

Comments suppressed due to low confidence (2)

src/libraries/Client/Microsoft.Agents.Client/HttpAgentClient.cs:187

• Consider adding a unit test to verify that the DeliveryMode is set to Stream when using SendActivityStreamedAsync, to catch regressions early.

activityClone.DeliveryMode = DeliveryModes.Stream;

src/libraries/Client/Microsoft.Agents.Client/HttpAgentClient.cs:186

• [nitpick] The variable name activityClone could be renamed to clonedActivity to align with common naming conventions and improve readability.

var activityClone = CreateSendActivity(agentConversationId, activity, relatesTo);