Exclude psu_id and recruit_type from the -4orcing process.

Addresses #4571.

psu_id and recruit_type are set further up the pipeline (specifically,
as an ApplyGlobalValuesFilter[1] in ncs_mdes_warehouse).  Setting it
here interferes with that process.

[1]: https://github.com/NUBIC/ncs_mdes_warehouse/blob/master/lib/ncs_navigator/warehouse/filters/apply_global_values_filter.rb#L45-L61