[Service Bus][Event Hubs] Refactoring among event-hubs and service-bus, cleanup related to "Tracing for Send"

[HarshaNalluru]

Followup for #11651
Note for both Event Hubs & Service Bus for improvements and to make changes for both packages at once:

• The name createMessageSpan() is slightly misleading as it may indicate that I can use it at any time when a message is involved. In reality, this method is tied to the "producer" kind, so is usable only when sending message.
• Also, jsdoc for this method would be helpful
• Why is config optional here? I would imagine that we would always have a ConnectionConfig
  • parentSpan is not a required parameter but feels primary, I believe that was the reason Chris made the config optional in event-hubs. We can make it the first param in both service-bus and event-hubs and make it required.
• For EventHubs, allow "null" value in the parentSpan in TryAddOptions
• ServiceBus cleanup
  • Now that we dont use the single send method from the MessageSender class anymore, it can be deleted. Same for sendMessages() method in the MessageSender class

Originally posted by @ramya-rao-a in #11651 (comment)

[github-actions]

Hi @HarshaNalluru, we deeply appreciate your input into this project. Regrettably, this issue has remained inactive for over 2 years, leading us to the decision to close it. We've implemented this policy to maintain the relevance of our issue queue and facilitate easier navigation for new contributors. If you still believe this topic requires attention, please feel free to create a new issue, referencing this one. Thank you for your understanding and ongoing support.