In DagBag set read_dags_from_db from config

[john-jac]

Update dagbag.py read_dags_from_db ini parameter to set from config rather than default to False. This will allow CLI backfill to work from stored DAGs and also matches the read_dags_from_db behavior to match that of the other DagBag input parameters.

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[boring-cyborg]

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[kaxil]

Hey John as mentioned on Slack, this won't be the correct fix,

read_dags_from_db decides if it should read the DAGs from DB (Serialized Dags from serialized_dag table). The conf.getboolean('core', 'STORE_DAG_CODE') config is only used in Webserver to show the Code (as plain strings) from the dag_code table.

[john-jac]

Not the correct solution