remove+replace `nccmp` from `fre/app/remap_pp_components/tests/test_remap_pp_components.py`

it's only used by the following tests/ test files

```
# fre/pp/tests/test_split_netcdf.py
test_split_file_data[ts_all]
test_split_file_data[ts_some]
test_split_file_data[static_all]
test_split_file_data[static_some]
test_split_file_metadata[all]
test_split_file_metadata[some]
test_split_file_metadata[static_all]
test_split_file_metadata[static_some]
```