Data_override test failures test

[uramirez8707]

Description
This attempts to fix the now consistent crashes with the data_override unit tests

FATAL from PE     1: NetCDF: Unknown file format: netcdf_file_open:INPUT/grid_spec.nc

The scripts now create the files, and then run the model rather than it all being the same run.

Fixes #1480

How Has This Been Tested?
CI (successfully passed the tests twice)

Checklist:

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• Any dependent changes have been merged and published in downstream modules
• New check tests, if applicable, are included
• make distcheck passes

[rem1776]

Thanks for separating this fix!