update parallel test code

Author: HydrogenSulfate

examples/water/dpa3/input_torch.json

@@ -85,7 +85,7 @@
       "batch_size": 1,
       "_comment": "that's all"
     },
-    "numb_steps": 1000000,
+    "numb_steps": 2000,
     "warmup_steps": 0,
     "gradient_max_norm": 5.0,
     "seed": 10,