Add wait_for_steps_completion option to EmrCreateJobFlowOperator.

[adrian-adikteev]

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Currently, when using wait_for_complition=True it will trigger the node to only wait until the cluster is successfully launched.
I added the option wait_for_steps_completion so that it will also await the cluster to be terminated successfully.

This is useful because it will eliminate the need to have an extra node in your DAG.

[boring-cyborg]

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[vincbeck]

Could you cover this new use case in a unit test?

[eladkal]

I think both wait_for_completion and wait_for_steps_completion can be very confusing.
If we are to support the new functionality I suggest to introduce a new parameter wait_policy which will accept value of wait_for_steps_completion, wait_for_steps_completed_and_machine_terminated similar to what we did with Kubernetes in #30718 when we had more than just a bool option for delete pod.

[vincbeck]

I like that idea!