Replace timedelta.max with year long timdelta in test_manager (#22527)
Replace timedelta.max with year long timdelta in test_manager (#22527)

Timedelta.max used in tests is not realistic and in some
circumstances, when it is added to date, it might cause
date OverflowError. Using long (but not 999999999 days long)
timedelta solves the problem.
cfei18/incubator-airflow,Acehaidrey/incubator-airflow,apache/airflow,danielvdende/incubator-airflow,apache/airflow,nathanielvarona/airflow,apache/airflow,lyft/incubator-airflow,nathanielvarona/airflow,danielvdende/incubator-airflow,cfei18/incubator-airflow,Acehaidrey/incubator-airflow,nathanielvarona/airflow,cfei18/incubator-airflow,cfei18/incubator-airflow,cfei18/incubator-airflow,lyft/incubator-airflow,apache/airflow,cfei18/incubator-airflow,nathanielvarona/airflow,nathanielvarona/airflow,apache/airflow,Acehaidrey/incubator-airflow,Acehaidrey/incubator-airflow,lyft/incubator-airflow,danielvdende/incubator-airflow,danielvdende/incubator-airflow,Acehaidrey/incubator-airflow,nathanielvarona/airflow,apache/airflow,lyft/incubator-airflow,Acehaidrey/incubator-airflow,danielvdende/incubator-airflow,danielvdende/incubator-airflow