test: remove @Ignore from passing HasManyDefaultMappedBySpec test

- The `HasManyDefaultMappedBySpec` test now passes, so the `@Ignore` annotation is no longer needed.

Author: matrei

grails-datastore-gorm-test/src/test/groovy/org/grails/datastore/gorm/HasManyDefaultMappedBySpec.groovy

@@ -5,11 +5,8 @@ import grails.persistence.Entity
 
 import org.grails.datastore.mapping.model.types.Association
 
-import spock.lang.Ignore
-
 class HasManyDefaultMappedBySpec extends GormDatastoreSpec {
 
-    @Ignore
     void "Test that has-many with multiple potential matches for the other side matches correctly"() {
 
         when:"A has many with multiple potential matching sides is retrieved"