Run integration tests with Kubernetes Executor too

[pankajkoti]

Please describe the feature you'd like to see
Currently, we run integration tests only on Celery Executor in our deployment. Customer is facing an issue with K8s executor on Runtime 7.3, details in Zendesk ticket.

We should also run integration tests (Example DAGs) on Kubernetes Executor to catch these issues early on.

Acceptance Criteria

• All checks and tests in the CI should pass
• Unit tests (90% code coverage or more, once available)
• Integration tests (if the feature relates to a new database or external service)
• Example DAG
• Docstrings in reStructuredText for each of methods, classes, functions and module-level attributes (including Example DAG on how it should be used)
• Exception handling in case of errors
• Logging (are we exposing useful information to the user? e.g. source and destination)
• Improve the documentation (README, Sphinx, and any other relevant)
• How to use Guide for the feature (example)