Crush out shared code in contact flows, especially transfer

Although the delta implies that this is actually adding code, it's
better than it looks, because some of the stuff in ContactFlowUtils
is duplicating more generic methods in ResourceFlowUtils, which
can be deleted when the domain and host flows are cut over.

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Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=133149104

java/google/registry/flows/contact/ContactCheckFlow.java

@@ -55,6 +55,6 @@ public class ContactCheckFlow extends LoggedInFlow {
       boolean unused = !existingIds.contains(id);
       checks.add(ContactCheck.create(unused, id, unused ? null : "In use"));
     }
-    return createOutput(Success, ContactCheckData.create(checks.build()), null);
+    return createOutput(Success, ContactCheckData.create(checks.build()));
   }
 }