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

Job	Run time
requests, python 3.8, ubuntu-20.04	41s
requests, python 3.9, ubuntu-20.04	56s
requests, python 2.7, ubuntu-20.04	1m 18s
requests, python 3.10, ubuntu-20.04	47s
requests, python 3.11, ubuntu-20.04	57s
requests, python 3.12, ubuntu-20.04	1m 19s
All requests tests passed or skipped	1s
	5m 59s

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