Add top-level option to bigquery_etl_query for replacing whole table

[jklukas]

See https://github.com/mozilla/telemetry-airflow/pull/982#discussion_r423706798

We have multiple places now where we set a group of options together in order to ensure bigquery_etl_query replaces a whole table rather than just a partition. It's becoming a common-enough pattern that it should have direct support.