Parse Change.Ids out of meta refs

This allows visible meta refs in VisibleRefFilter.

Change-Id: Ia7a0a0027109a85204882c8a69b03292a29ece92

gerrit-server/src/main/java/com/google/gerrit/server/notedb/ChangeNoteUtil.java

@@ -39,7 +39,7 @@ public class ChangeNoteUtil {
     r.append(m);
     r.append('/');
     r.append(n);
-    r.append("/meta");
+    r.append(RefNames.META_SUFFIX);
     return r.toString();
   }