[dev/emc]: Upgrade UFS WM to spack-stack v2.1.0

[gspetro-NOAA]

Is your feature request related to a problem? Please describe.
The UFS WM needs to upgrade to spack-stack v2.1.0. This issue will track required changes for atmos_cubed_sphere.

• spack-stack v2.1.0 uses FMS 2025.03, which removed sst_anom and sst_ncep from the amip_interp code (Remove sst_anom and sst_ncep from the amip_interp code.  FMS#1695).

Describe the solution you'd like

• sst_anom and sst_ncep must be removed from atmos_cubed_sphere routines

Describe alternatives you've considered
None

Additional context
Add any other context or screenshots about the feature request here.