[dagster-airflow] Fix k8s pod operator in dagster-airflow and get it under test
well, it only took me 30 diffs, but this is now working and ready for review.
This diff fixes the Dagster k8s operator and provides a kind-based unit test, getting it under test.
To speed up this test, I've also moved the Docker image build step out to the nightly; it was getting extremely slow.
Test Plan: unit
Reviewers: alangenfeld, max
Reviewed By: alangenfeld
Differential Revision: https://dagster.phacility.com/D1429