sc_r, Cs_r -> sc_rho, Cs_rho?
I find it quite inconsistent to use the location suffix _rho for most variables but not for sc_r and Cs_r:
- https://gitlab.inria.fr/croco-ocean/croco/-/blob/master/OCEAN/def_grid_3d.F#L177
- https://gitlab.inria.fr/croco-ocean/croco/-/blob/master/OCEAN/def_grid_3d.F#L197
Fixing it won't break codes that use the formula_terms attribute.