fix(references) Avoid logging removal of references tab

It’s not really removed so it’s useless log/audit

issue #5817

plugins/generic/references/class_reference.inc

@@ -83,6 +83,12 @@ class reference extends simplePlugin
 
   function save()
   {
+    return array();
+  }
+
+  function remove($fulldelete = FALSE)
+  {
+    return array();
   }
 }