Database specific response for REST APIv1 CoGroup

Attempting to view a CoGroup per CO Person with an invalid CoPersonId returns 404 on PostgreSQL but 200 on MariaDB.

Example request and response on MariaDB with invalid / non-existent CoPersonId "999" :

[Request] GET https://comanage-registry:443/registry/co_groups.json?copersonid=999

[Response] 200

[Response] {"ResponseType":"CoGroups","Version":"1.0","CoGroups":[]}