tests: move init_models to setUpModule #7425

Job	Run time
Test Python (1, 3.8)	11m 4s
Test Python (1, 3.11)	11m 35s
Test Python (2, 3.8)	10m 54s
Test Python (2, 3.11)	9m 57s
Test Python (3, 3.8)	9m 16s
Test Python (3, 3.11)	8m 39s
Test Python (4, 3.8)	10m 49s
Test Python (4, 3.11)	10m 45s
Test Python (5, 3.8)	10m 18s
Test Python (5, 3.11)	9m 36s
Test Python (6, 3.8)	10m 14s
Test Python (6, 3.11)	9m 44s
Combine and update integration test durations (3.8)	3s
Combine and update integration test durations (3.11)	7s
Pass testing Python	2s
	2h 3m 3s

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