Fix occasional TestParseShadow failures (=> findItemDefinitionByType)

This code https://github.com/Evolveum/midpoint/blob/d28cc36128755006558e6c147dbd53b72abf688c/infra/prism-impl/src/main/java/com/evolveum/midpoint/prism/impl/schema/PrismSchemaImpl.java#L394 should first select non-deprecated definitions, and only then deprecated ones.

Otherwise schema parsing tests (occasionally) fail. The reason is that the ordering of item definitions within schema is nondeterministic (taken from HashMap in schema parser).