update test expectation

Signed-off-by: Harshit Gangal <[email protected]>

go/vt/vtgate/planbuilder/testdata/select_cases.json

@@ -83,7 +83,7 @@
               "Sharded": true
             },
             "FieldQuery": "select * from `user` as u, user_metadata as um where 1 != 1",
-            "Query": "select * from `user` as u, user_metadata as um where foo = 41 and u.id = um.user_id limit 20",
+            "Query": "select * from `user` as u, user_metadata as um where foo = 41 and u.id = um.user_id limit :__upper_limit",
             "Table": "`user`, user_metadata"
           }
         ]