test: add end-to-end test

Signed-off-by: Andres Taylor <[email protected]>

go/test/endtoend/vtgate/vitess_tester/aggregation/aggregation.test

@@ -61,4 +61,7 @@ from (select 1 as one
 
 select u.id, u.t1_id, t.num_segments
 from (select id, count(*) as num_segments from t1 group by 1 order by 2 desc limit 20) t
-         join t2 u on u.id = t.id;
+         join t2 u on u.id = t.id;
+
+select name
+from (select name from t1 group by name having count(t1.id > 1)) t1;