Use of "DDL delegates" can lead to unexpected behavior (managed tables not being dropped)

A "ddl delegate" provides ddl related functionality that isn't in Hive. For example Kudu tables use ddl delegate to create and drop tables in Kudu. If a user were to somehow create a Kudu table in Hive and that table metadata wasn't loaded in Impala, then the user dropped the entire database using "cascade" through Impala, then the Kudu table would remain. Eventually Hive should support Kudu tables and the "ddl delegate" can be removed.