Concurrency settings in FlowETL config are ignored

[maxalbert]

The FlowETL config allows to set a concurrency parameter for each supported CDR type. However, this is currently ignored. It should be passed on to the DAG when it is created in order to limit the number of concurrent DAG runs for each CDR type. (In the future we may also want a global concurrency setting, but having the ability to limit ingestion on a per CDR type basis should be sufficient for now.)