Use label rather than name when sorting custom properties in agreements

To be consistent with user expectations and licenses, Agreement Supplementary Properties should sort by label, rather than by name

Compare https://github.com/folio-org/mod-licenses/blob/7533fa68df36ed7d92f80331db1428c4c6654262/service/grails-app/controllers/org/olf/licenses/CustomPropertDefinitionController.groovy#L30

to

https://github.com/folio-org/mod-agreements/blob/70df778955c77d43d746b59efd8d4cfb7a2a7602/service/grails-app/controllers/org/olf/CustomPropertDefinitionController.groovy#L30

Licenses has the correct behaviour using label rather name