* and stop setting default values in python operator code, so defaults can be set at the server side.

This issue is just for the PR and questions from maintainers. 
setup.py
]
databricks = [
    'requests>=2.26.0, <3',
]
datadog = [
    'datadog>=0.14.0',
]
deprecated_api = [
    'requests>=2.26.0',
]
doc = [
    
    'sphinx>=2.1.2, <3.5.0',
    'sphinx-airflow-theme',
    'sphinx-argparse>=0.1.13',
    'sphinx-autoapi==1.0.0',
    'sphinx-copybutton',
    'sphinx-jinja~=1.1',
    'sphinx-rtd-theme>=0.1.6',
    'sphinxcontrib-httpdomain>=1.7.0',
    'sphinxcontrib-redoc>=1.6.0',
    'sphinxcontrib-spelling==7.2.1',
]
docker = [
    'docker',
]
drill = ['sqlalchemy-drill>=1.1.0', 'sqlparse>=0.4.1']
druid = [
    'pydruid>=0.4.1',
]