Changed mysql-test to print warnings for not existing table to DROP TABLE

Cleaned up test; Removed wrong DROP TABLE commands and use standard table and database names.
changed store_warning() -> push_warning_print()

mysql-test/r/rename.result

@@ -37,3 +37,5 @@ select * from t3;
 3	table 3
 3	table 3
 drop table if exists t1,t2,t3,t4;
+Warnings:
+Note	1051	Unknown table 't4'