Fix EmrAddStepsOperature wait_for_completion parameter is not working

[2h-kim]

When use airflow with EmrAddStepsOperature with wait_for_completion=False it isn't work because in excute, add_job_flow_steps function use wait_for_completion=True.
When modified, it was confirmed that it turned well.

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[vincbeck]

Nice catch! Could you add a unit test? Having a unit would have avoided this issue :)

[2h-kim]

Nice catch! Could you add a unit test? Having a unit would have avoided this issue :)

@vincbeck
I added unit test code by referring to your advice. But it's my first time unit test with mock, so can you check if I wrote it well? :)

[Taragolis]

@2h-kim also static checks failed. You should follow STATIC_CODE_CHECKS guide and install pre-commit, unless you want to change everything manually.

[2h-kim]

@Taragolis Thank you for your kind explanation. As you said, I used 'pre-commit' and checked that there is a quote(') problem.

[potiuk]

Still a static check to fix :(

[eladkal]

Rebased the PR as it was too far behind main.
will merge once CI is green

[boring-cyborg]

Awesome work, congrats on your first merged pull request!

[deban9017]

Hey, I think you probably forgot to test for wait_for_completion = true case.