fix: Fix breadcrumb timestamp casting and its tests #3907

Job	Run time
Data Processing (latest) (3.6, ubuntu-20.04)	1m 12s
Data Processing (latest) (3.7, ubuntu-20.04)	2m 6s
Data Processing (latest) (3.8, ubuntu-20.04)	3m 45s
Data Processing (latest) (3.10, ubuntu-20.04)	2m 46s
Data Processing (pinned) (3.6, ubuntu-20.04)	3m 12s
Data Processing (pinned) (3.7, ubuntu-20.04)	3m 34s
Data Processing (pinned) (3.8, ubuntu-20.04)	3m 42s
Data Processing (latest) (3.11, ubuntu-20.04)	4m 50s
Data Processing (pinned) (3.9, ubuntu-20.04)	2m 4s
Data Processing (latest) (3.12, ubuntu-20.04)	4m 55s
Data Processing (pinned) (3.10, ubuntu-20.04)	3m 57s
Data Processing (pinned) (3.11, ubuntu-20.04)	4m 15s
Data Processing (pinned) (3.12, ubuntu-20.04)	3m 25s
All Data Processing tests passed	1s
	43m 44s

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