Use FDScheme when calling SurfaceFluxes

[LenkaNovak]

As found by @gdecker1 and @akshaysridhar , we are not calling FDScheme (correct for our vertical discretization) when calculating surface fluxes in ClimaAtmos, which assumes the default scheme (FVScheme).

@kmdeck, this may be relevant to you guys as well (though in practice it shouldn't change your values much).

[szy21]

This has been updated in #2261