copy_schema_to_ca: Fallback to old import location for ipaplatform.services
This file is copied to older servers that might not have the ipaplatform
refactoring.
Import from the old location if the new one is not available.
https://fedorahosted.org/freeipa/ticket/4763
Reviewed-By: Tomas Babej <tbabej@redhat.com>