[server/rql2sql] use VariableRef.is_equivalent explicitly instead of relying on __eq__ What we want to compare is the variable referenced by the VariableRef, we should make that explicit. Closes #6694406

sync_schema_props_perms(('State', 'state_of', 'Workflow'), commit=False)
sync_schema_props_perms(('State', 'name', 'String'))