(answer changing for DGLC compsets) Update the model_datafiles_list file used for DGLC Greenland grids to remove the ice shelves

@gunterl will update the model_datafiles_list file used for Greenland from

```
$DIN_LOC_ROOT/glc/cism/Greenland/[greenland_4km_epsg3413_c251001.nc
```

to a file that removes the floating ice shelves. Once, that's done @Katetc can make a PR here pointing to that file.