Add duo agent platform create and start events

What does this MR do and why?

This MR adds duo agent platform create and start events.

References

Related to #560731 (closed)

Screenshots or screen recordings

Create event

Start event

Cleanup event

This MR also passes workflow definition to the existing cleanup_stuck_agent_platform_session event's label

How to set up and validate locally

1. Run an agent platform session
2. You should see create_agent_platform_session and start_agent_platform_session events. -->

MR acceptance checklist

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