Use sys.exit() instead of exit() (#10414)
Use sys.exit() instead of exit() (#10414)

The `exit` and `quit` functions are actually `site.Quitter` objects and are loaded, at interpreter start up, from `site.py`. However, if the interpreter is started with the `-S` flag, or a custom `site.py` is used then `exit` and `quit` may not be present. It is recommended to use `sys.exit()` which is built into the interpreter and is guaranteed to be present.

Previously, `exit()` was used and wouls fail if the interpreter is passed the `-S` option.
dhuang/incubator-airflow,cfei18/incubator-airflow,bolkedebruin/airflow,nathanielvarona/airflow,airbnb/airflow,mrkm4ntr/incubator-airflow,lyft/incubator-airflow,DinoCow/airflow,apache/airflow,bolkedebruin/airflow,apache/incubator-airflow,danielvdende/incubator-airflow,bolkedebruin/airflow,lyft/incubator-airflow,mrkm4ntr/incubator-airflow,mistercrunch/airflow,DinoCow/airflow,apache/incubator-airflow,apache/airflow,nathanielvarona/airflow,dhuang/incubator-airflow,apache/airflow,danielvdende/incubator-airflow,mistercrunch/airflow,mrkm4ntr/incubator-airflow,airbnb/airflow,Acehaidrey/incubator-airflow,Acehaidrey/incubator-airflow,lyft/incubator-airflow,mrkm4ntr/incubator-airflow,dhuang/incubator-airflow,cfei18/incubator-airflow,lyft/incubator-airflow,apache/airflow,DinoCow/airflow,cfei18/incubator-airflow,sekikn/incubator-airflow,nathanielvarona/airflow,Acehaidrey/incubator-airflow,cfei18/incubator-airflow,nathanielvarona/airflow,danielvdende/incubator-airflow,Acehaidrey/incubator-airflow,mistercrunch/airflow,apache/airflow,apache/incubator-airflow,danielvdende/incubator-airflow,apache/incubator-airflow,nathanielvarona/airflow,airbnb/airflow,Acehaidrey/incubator-airflow,Acehaidrey/incubator-airflow,sekikn/incubator-airflow,nathanielvarona/airflow,DinoCow/airflow,bolkedebruin/airflow,apache/airflow,danielvdende/incubator-airflow,cfei18/incubator-airflow,sekikn/incubator-airflow,mistercrunch/airflow,bolkedebruin/airflow,cfei18/incubator-airflow,dhuang/incubator-airflow,sekikn/incubator-airflow,airbnb/airflow,danielvdende/incubator-airflow