Don't indicate clean-up is done till it is

[bbangert]

Cleanup will update a service to zero, and then delete it. However, it's not actually fully shut-down yet.

"Unable to Start a service that is still draining" will occur if a load-test is immediately started again on the cluster with the same names as the prior one can still be winding down.

The Clean-up step should ensure all services/ task-defs are fully drained before completing. Perhaps with another lambda that repeats after the Clean-up which checks and retries until it sees everything completely shutdown.