Read timezone for Crons monitors from `celery_schedule` if existing #3960

Job	Run time
redis, python 2.7, ubuntu-20.04	2m 45s
redis, python 3.7, ubuntu-20.04	1m 27s
redis, python 3.8, ubuntu-20.04	1m 39s
redis, python 3.9, ubuntu-20.04	1m 55s
redis, python 3.10, ubuntu-20.04	46s
redis, python 3.11, ubuntu-20.04	1m 2s
redis, python 3.12, ubuntu-20.04	1m 0s
All redis tests passed or skipped	1s
	10m 35s

Provide feedback