Remove t3 in join_nested.test

mysql-test/r/join_nested.result:
  Remove t3 too.
mysql-test/t/join_nested.test:
  Remove t3 too.

mysql-test/r/join_nested.result

@@ -1466,4 +1466,4 @@ id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	SIMPLE	t4	ref	a	a	5	test.t3.b	X	
 1	SIMPLE	t6	ref	a	a	5	test.t4.b	X	
 1	SIMPLE	t5	ref	a	a	5	test.t3.b	X	
-drop table t0, t1, t2, t4, t5, t6, t7;
+drop table t0, t1, t2, t3, t4, t5, t6, t7;

mysql-test/t/join_nested.test

@@ -899,4 +899,4 @@ explain select * from t2 left join
   (t3 left join (t4 join t6 on t6.a=t4.b) on t4.a=t3.b 
    join t5 on t5.a=t3.b) on t3.a=t2.b;
 
-drop table t0, t1, t2, t4, t5, t6, t7;
+drop table t0, t1, t2, t3, t4, t5, t6, t7;