fix: remove lmp_traj from forward_files in run_md_model_devi

[HuangJiameng]

lmp_traj should not be in forward_files in run_model_devi step.

[HuangJiameng]

This fix aims to solve the problem mentioned in #938.

[codecov-commenter]

Codecov Report

Merging #944 (45cebde) into devel (6347ba8) will not change coverage.
The diff coverage is 0.00%.

@@           Coverage Diff           @@
##            devel     #944   +/-   ##
=======================================
  Coverage   38.16%   38.16%           
=======================================
  Files          99       99           
  Lines       17885    17885           
=======================================
  Hits         6825     6825           
  Misses      11060    11060           

Impacted Files	Coverage Δ
dpgen/generator/run.py	62.00% <0.00%> (ø)

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[njzjz]

This PR is incorrect - LAMMPS will throw errors when the directory does not exist.

[wanghan-iapcm]

@HuangJiameng have you really tested this PR?

[HuangJiameng]

I have tested it with model_devi_merge_traj = true. I see, I will fix it.

[HuangJiameng]

This PR is incorrect - LAMMPS will throw errors when the directory does not exist.

This error will occur when model_devi_merge_traj = false