Read timezone for Crons monitors from `celery_schedule` if existing #3952

Job	Run time
sqlalchemy, python 3.7, ubuntu-20.04	1m 36s
sqlalchemy, python 2.7, ubuntu-20.04	1m 55s
sqlalchemy, python 3.8, ubuntu-20.04	2m 11s
sqlalchemy, python 3.9, ubuntu-20.04	1m 52s
sqlalchemy, python 3.10, ubuntu-20.04	1m 47s
sqlalchemy, python 3.11, ubuntu-20.04	2m 27s
sqlalchemy, python 3.12, ubuntu-20.04	1m 10s
All sqlalchemy tests passed or skipped	1s
	12m 59s

Provide feedback