fix(dp): fix dp seed in dpa2 descriptor (deepmodeling#3957)

<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->

## Summary by CodeRabbit

- **New Features**
- Introduced a `seed` parameter to enhance the initialization process,
enabling more controlled and reproducible results.

<!-- end of auto-generated comment: release notes by coderabbit.ai -->

deepmd/dpmodel/descriptor/dpa2.py

@@ -476,6 +476,7 @@ def init_subclass_params(sub_data, sub_class):
                 self.repformers.dim_in,
                 bias=False,
                 precision=precision,
+                seed=child_seed(seed, 3),
             )
         self.tebd_transform = None
         if self.add_tebd_to_repinit_out:
@@ -484,6 +485,7 @@ def init_subclass_params(sub_data, sub_class):
                 self.repformers.dim_in,
                 bias=False,
                 precision=precision,
+                seed=child_seed(seed, 4),
             )
         assert self.repinit.rcut > self.repformers.rcut
         assert self.repinit.sel[0] > self.repformers.sel[0]