[LFRic] [PSyAD] Adjoint tests do not split element order

[DrTVockerodtMO]

Once LFRic 4443 is merged, the get_fs will take in a horizontal and vertical element order instead of just the element_order namelist variable. This is not expected to be merged before LFRic vn2.1 so this does not need to be addressed for PSyclone 3.0, but does need to be addressed.

The adjoint tests use the get_fs method. These method calls and the validation testing them will need to be changed to incorporate this new format.