* Add back comments and cleanup canary event test

* Fix Canary events unit test side effects

rendering templates on unmapped task creates
somewhat a new session which prevents other
tests from running properly

RuntimeError: Session already set for this task.
You can only have one 'set_current_task_session'
context manager active at a time.

* Linting

* Remove mapped preparation tasks in new Refine

* Remove mapped preparation tasks in Canary events

It's an optimization for our Airflow setup.

This commit also converts a SimpleSkeinOperator into a SparkSubmitOperator in canary event.