chore(lmp): add LAMMPS DPA-2 nopbc tests (#4220)

Adding tests to see whether #4167 is resolved. The answer is no.
Segfaults are thrown with MPI.

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

## Summary by CodeRabbit

- **New Features**
- Introduced a new command-line argument `--nopbc` to modify boundary
conditions in LAMMPS simulations.
- **Tests**
- Added a comprehensive suite of unit tests for the DeepMD potential in
LAMMPS, covering various configurations and scenarios to ensure accuracy
and reliability.

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

---------

Signed-off-by: Jinzhe Zeng <[email protected]>

source/lmp/tests/run_mpi_pair_deepmd.py

@@ -21,6 +21,7 @@
 parser.add_argument("MD_FILE", type=str)
 parser.add_argument("OUTPUT", type=str)
 parser.add_argument("--balance", action="store_true")
+parser.add_argument("--nopbc", action="store_true")
 
 args = parser.parse_args()
 data_file = args.DATAFILE
@@ -38,7 +39,10 @@
     # 6 and 0 atoms
     lammps.processors("1 2 1")
 lammps.units("metal")
-lammps.boundary("p p p")
+if args.nopbc:
+    lammps.boundary("f f f")
+else:
+    lammps.boundary("p p p")
 lammps.atom_style("atomic")
 lammps.neighbor("2.0 bin")
 lammps.neigh_modify("every 10 delay 0 check no")