truncate test made independed from environment

mysql-test/t/truncate.test

@@ -1,6 +1,7 @@
 #
 # Test of truncate
 #
+drop table if exists t1;
 create table t1 (a integer, b integer,c1 CHAR(10));
 insert into t1 (a) values (1),(2);
 truncate table t1;