Python: improve workflow validation around cycles detected

[moonbox3]

We want the workflow validation logic to be easy to understand and actionable. However, for some of the OOB patterns, like Handoff or Magentic, we receive a warning like:

"Cycle detected in the workflow graph involving: agent_travel_summary_agent -> agent_language_agent -> agent_local_agent -> magentic_orchestrator -> agent_travel_summary_agent. Ensure termination or iteration limits exist."

It's not immediately clear to a dev if they need to take action or not. Let's improve this.