* 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. 
tests/providers/yandex/operators/test_yandexcloud_dataproc.py
operator = DataprocCreateMapReduceJobOperator(
            task_id='run_mapreduce_job',
            main_class='org.apache.hadoop.streaming.HadoopStreaming',
            file_uris=[
                's3a://some-in-bucket/jobs/sources/mapreduce-001/mapper.py',
                's3a://some-in-bucket/jobs/sources/mapreduce-001/reducer.py',
            ],