CORE-5832 Updated /apps/categories response.

Renamed the "groups" key to "categories".
CORE-5832 Updated Donkey forwarded requests.

Updated forwarded requests in the new Donkey endpoints so that not all query parameters are forwarded, since the new metadactyl endpoints have stricter query param validation.
Renamed sortField and sortDir metadactyl query params to sort-field and sort-dir.