Use verbose 20xx creation date for e3sm_to_cmip maps

[xylar]

Checklist

• Document (in a comment titled Testing in this PR) any testing that was used to verify the changes

[xylar]

I can't test this very easily until LCRC maintenance is over today.

[xylar]

Testing

This fix, while a little crude, will work fine for the next 75 years or so.

I tested on the EC30to60E2r2 (and r3) mesh in:

/lcrc/group/e3sm/ac.xylar/compass_1.2/chrysalis/test_20230314/files_for_e3sm_more_parts

As expected, I see the full year:

$ ls ec30to60e2r2/ocean/global_ocean/files_for_e3sm/assembled_files/diagnostics/maps/
map_EC30to60E2r2_to_cmip6_180x360_aave.20230313.nc
map_EC30to60E2r2_to_cmip6_180x360_mono.20230313.nc
map_EC30to60E2r2_to_cmip6_180x360_nco.20230313.nc