fix(test): drop a duplicated assignment and a stale ownership docstring

- The harness extraction emitted `data_file_empty_rank` twice in a row: the
  preserved comment block already carried the assignment and the rewrite
  template added it again. A runtime no-op, but a patch artifact in the
  commit whose point was a clean single-owner harness.
- TestNativeSpinWithBridging still described `get_standard_model` as the
  owner of the bridging composition, which is the opposite of the contract
  this branch establishes: that builder now rejects `bridging_method`, and
  `get_native_spin_model` routes DPA4/SeZM to `get_sezm_model` and
  re-classes the composition it returns.

Author: Han Wang

source/lmp/tests/test_lammps_dpa4_spin_graph_pt2.py

@@ -92,7 +92,6 @@
 # phantom path and none trips the genuinely-empty fail-fast.  The shifted
 # coordinates (``coord_empty_rank``) are defined below, after ``coord``.
 data_file_empty_rank = Path(__file__).parent / "data_dpa4_spin_graph_pt2_empty_rank.lmp"
-data_file_empty_rank = Path(__file__).parent / "data_dpa4_spin_graph_pt2_empty_rank.lmp"
 # The MPI runner is graph-spin-specific (no aparam / no NULL-type
 # extras, unlike run_mpi_pair_deepmd_spin_dpa3_pt2.py's virtual-atom-scheme
 # runner): the native-spin DPA4 fixture takes no fparam/aparam.

source/tests/pt_expt/model/test_zbl_bridging.py

@@ -275,10 +275,12 @@ def _spin_system():
 class TestNativeSpinWithBridging:
     """Native spin + analytical bridging compose (review 3649276109).
 
-    ``get_standard_model`` OWNS assembling the atomic model, bridging
-    composition included, and the native-spin wrapper re-classes whatever it
-    returns -- so the two features combine with no special case: the learned
-    child consumes ``spin``, the analytical child accepts and ignores it.
+    ``get_sezm_model`` OWNS the bridging composition (``get_standard_model``
+    rejects ``bridging_method``: a composition is not expressible on a
+    non-composite model type). ``get_native_spin_model`` routes DPA4/SeZM
+    configs there and then RE-CLASSES the returned composition -- so the two
+    features combine with no special case: the learned child consumes
+    ``spin``, the analytical child accepts and ignores it.
     """
 
     def test_construction_composes_and_keeps_spin(self) -> None: