Update api-ref for cyborg

Cyborg has now published their api-ref at the default location[0], drop
the old override.

[0] https://docs.openstack.org/api-ref/accelerator/

Signed-off-by: Dr. Jens Harbott <harbott@osism.tech>
Change-Id: I93b0d4c021f710667d4b8e0f8e78f16dc3b7fa67

service-types.yaml

@@ -140,7 +140,6 @@ services:
   project: qinling
 - service_type: accelerator
   project: cyborg
-  api_reference: https://docs.openstack.org/cyborg/latest/admin/api.html
 - service_type: admin-logic
   project: adjutant
   aliases: