minor #5703 comment old logic (OskarStark)

This PR was merged into the 2.7 branch.

Discussion
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comment old logic

because it's already commented in line 123

Commits
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4e1932c comment old logic

Author: xabbuh

reference/constraints/Callback.rst

@@ -150,10 +150,12 @@ have access to the object instance, they receive the object as the first argumen
             ;
 
             // If you're using the old 2.4 validation API
+            /*
             $context->addViolationAt(
                 'firstName',
                 'This name sounds totally fake!'
             );
+            */
         }
     }