* 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 = DataprocCreateSparkJobOperator(
            task_id='create_spark_job',
            main_jar_file_uri='s3a://data-proc-public/jobs/sources/java/dataproc-examples-1.0.jar',
            main_class='ru.yandex.cloud.dataproc.examples.PopulationSparkJob',
            file_uris=[
                's3a://some-in-bucket/jobs/sources/data/config.json',
            ],
            archive_uris=[
                's3a://some-in-bucket/jobs/sources/data/country-codes.csv.zip',
            ],
            jar_file_uris=[
                's3a://some-in-bucket/jobs/sources/java/icu4j-61.1.jar',
                's3a://some-in-bucket/jobs/sources/java/commons-lang-2.6.jar',
                's3a://some-in-bucket/jobs/sources/java/opencsv-4.1.jar',
                's3a://some-in-bucket/jobs/sources/java/json-20190722.jar',
            ],
            args=[
                's3a://some-in-bucket/jobs/sources/data/cities500.txt.bz2',
                's3a://some-out-bucket/dataproc/job/results/${{JOB_ID}}',
            ],
            properties={
                'spark.submit.deployMode': 'cluster',
            },
        )
        context = {'task_instance': MagicMock()}
        context['task_instance'].xcom_pull.return_value = 'my_cluster_id'