Sets the run_id for a DAG invoked in Airflow to the same ULID assigned
to it in Shipyard. While this was already happening as a parameter to
the DAG being invoked, by making it the run_id, further correlation is
possible, at a level that both Shipyard and the Airflow framework are
aware.
As part of making this change, fragility was uncovered in the
rest_api_plugin that expedited the need to switch to the built-in, but
experimental airflow API to trigger a dag (one of two API endpoints
provided - this is important later in this story). In any case, the 3rd
party rest_api_plugin was removed.
As a result of the rest_api_plugin being removed:
1) the simpleton helm test to check the api of airflow was also removed
(it used the version endpoint of this plugin). As the built-in api
provides no version endpoint or similarly accessible-without-being-stateful
endpoint, the helm test had no new place to look for something to call.
2) Some clean up of exclusions and documentation was possible - test
coverage, security exclusions, left over documentation remnants
Change-Id: I0b68496a8500408b776b4acc12888aa017c4c7d2
e59fb314c1