Check scream input files on input data servers for consistency.

I chased a bug that was eventually due to a bad file on the ANL server. The file was `spa_data_for_testing.nc`, which on ANL servers did not contain important stuff (e.g., the dimensions `n_a` and `n_b`).

I suppose that file got changed at some point, without adding a timestamp to the name, but simply replacing the existing one. The file must have been uploaded on _some_ servers, but now all. For some reason, my machine was pinging ANL server first, while our testbeds must have pinged a different one first (finding the new file).

In general, we need to be careful with updating files without changing the filename. I know E3SM doesn't allow this, while we are ok with it while we develop scream v1. However, changing input files can have side effects like this one.