Remove sst_ncep and sst_anom from amip_interp_mod

[laurenchilutti]

Describe the bug
sst_ncep and sst_anom should not be in amip_interp_mod and should be defined by the model components. Right now the dycore and the ice model seem to be the only components using these variables and they are defined in their respective components.

To Reproduce
Look at the code:

https://github.com/NOAA-GFDL/GFDL_atmos_cubed_sphere/blob/9af882c63615925e75a6b812ab4ab227a113f454/model/fv_grid_utils.F90#L210-L211

https://github.com/NOAA-GFDL/FMScoupler/blob/main/simple/ice_model.F90#L95

Expected behavior
sst_ncep and sst_anom should not be defined anywhere in FMS. We leave it up to components to define/allocate.

System Environment
N/A

Additional context
This change should not require any component updates.

[laurenchilutti]

You can assign this issue to me