Fix relatedResouce for HasMetadatFor
Each network has one RelatedResource HasMetadatFor
(scheme XML).
The url would be : https://ws.resif.fr/fdsnws/station/1/query?net=FR&level=station
or https://ws.resif.fr/fdsnws/station/1/query?net=1A&level=station&startbefore...
see doc
This is automated by Dalima, thus simplifying the RelatedResource formset (removing the scheme field, IsMetadataFor wont be used).