[AIRFLOW-5349] Added schedulername option for KubernetesPodOperator

[antonymayi]

Make sure you have checked all steps below.

Jira

• My PR addresses the following Airflow Jira issues and references them in the PR title. For example, "[AIRFLOW-XXX] My Airflow PR"
  • https://issues.apache.org/jira/browse/AIRFLOW-5349

Description

• Here are some details about my PR, including screenshots of any UI changes:

Kubernetes PODs might be specified with explicit scheduler. This feature, however, is currently not available from the KubernetesPodOperator API.

I am offering simple PR that adds this option via a schedulername parameter.

Tests

• My PR adds the following unit tests:
  • tests.minikube.test_kubernetes_pod_operator.test_pod_schedulername

Commits

• My commits all reference Jira issues in their subject lines, and I have squashed multiple commits if they address the same issue. In addition, my commits follow the guidelines from "How to write a good git commit message":
  1. Subject is separated from body by a blank line
  2. Subject is limited to 50 characters (not including Jira issue reference)
  3. Subject does not end with a period
  4. Subject uses the imperative mood ("add", not "adding")
  5. Body wraps at 72 characters
  6. Body explains "what" and "why", not "how"

Documentation

• In case of new functionality, my PR adds documentation that describes how to use it.
  • All the public functions and the classes in the PR contain docstrings that explain what it does
  • If you implement backwards incompatible changes, please leave a note in the Updating.md so we can assign it to a appropriate release

Code Quality

• Passes flake8

[mik-laj]

Hi. This PR appears to contain unrelated changes. Could you look at it?

[antonymayi]

I am replacing this PR with #6088