fix(pt): fix global bias stat with different natom #8370

Job	Run time
Test Python (1, 3.8)	24m 27s
Test Python (1, 3.11)	22m 52s
Test Python (2, 3.8)	24m 14s
Test Python (2, 3.11)	22m 52s
Test Python (3, 3.8)	23m 7s
Test Python (3, 3.11)	21m 47s
Test Python (4, 3.8)	25m 31s
Test Python (4, 3.11)	22m 19s
Test Python (5, 3.8)	23m 54s
Test Python (5, 3.11)	22m 30s
Test Python (6, 3.8)	22m 40s
Test Python (6, 3.11)	22m 54s
Combine and update integration test durations (3.8)	16s
Combine and update integration test durations (3.11)	21s
Pass testing Python	2s
	4h 39m 46s

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