* add AIRFLOW_VAR_ prefix to env vars in minimal blueprint
* update DAGs for env vars in minimal blueprint
* add AIRFLOW_VAR_ prefix to env vars in foundation blueprint
* update DAGs for env vars in foundation blueprint
* apply tf linting
---------
Co-authored-by: lcaggio <lorenzo.caggioni@gmail.com>
Co-authored-by: Ludovico Magnocavallo <ludomagno@google.com>