ndb - make sure all used tables are dropped in beginning of test case

mysql-test/r/ndb_index_unique.result

-drop table if exists t1, t2, t3, t4, t5, t6, t7;
+drop table if exists t1, t2, t3, t4, t5, t6, t7, t8;
 CREATE TABLE t1 (
 a int unsigned NOT NULL PRIMARY KEY,
 b int unsigned not null,