Read timezone for Crons monitors from `celery_schedule` if existing #3953

Job	Run time
falcon, python 2.7, ubuntu-20.04	1m 31s
falcon, python 3.5, ubuntu-20.04	1m 56s
falcon, python 3.6, ubuntu-20.04	1m 51s
falcon, python 3.7, ubuntu-20.04	1m 29s
falcon, python 3.8, ubuntu-20.04	1m 16s
falcon, python 3.9, ubuntu-20.04	1m 4s
falcon, python 3.10, ubuntu-20.04	1m 32s
falcon, python 3.11, ubuntu-20.04	1m 1s
falcon, python 3.12, ubuntu-20.04	3m 51s
All falcon tests passed or skipped	1s
	15m 32s

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