General Issue: Next stage of deprecation cycles

[manciniedoardo]

Background Information

derive_var_afeye() is the only function with deprecations, these needs to be updated according to the deprecation cycle here.

Definition of Done

• derive_var_afeye(): lat_vals and dataset arguments now need to throw errors rather than warnings.
• unit tests for these deprecations need to be updated too to test the error-throwing.