hofx_two_vars_obs.nc not in use - add test or remove data

[twsearle]

          > > @mikecooke77 I am not sure why this is passing the tests - I still see a `datetime` and `time` variables rather than a `dateTime` variable in `hofx_two_vars_obs.nc`. Is that expected?

I believe this file is no longer used. Would you like me to update it or remove it?

If you can update it that would be best if not too much trouble - I will figure out if I need it (add a test) or delete it later.

Originally posted by @twsearle in #137 (comment)