[GCMPY] Update POST_P and PLOT_P at NCCS

[mathomp4]

In #851, one thing that happened was a change to POST_P and PLOT_P:

              setenv    POST_P  "SBATCH --nodes=1 --ntasks-per-node=${NCPUS_PER_NODE}"        # PE Configuration for gcm_post.j
              if      ($MODEL == 'mil') then
                 setenv PLOT_P  "SBATCH --constraint=${MODEL} --nodes=1 --ntasks-per-node=24 --mem=488G"  # PE Configuration for gcm_plot.j
              else if ($MODEL == 'cas') then
                 setenv PLOT_P  "SBATCH --constraint=${MODEL} --nodes=1 --ntasks-per-node=10 --mem=185G"  # PE Configuration for gcm_plot.j
              else
                 setenv PLOT_P  "SBATCH --nodes=4 --ntasks=4"                                 # PE Configuration for gcm_plot.j
              endif

This should be reflected in the Python scripting effort.