DROP TABLE should also drop BATCH prepared statements associated to it

When a Keyspace or Column Family is dropped, Cassandra should evict the cached prepared statements that reference that keyspace and/or table as partially solved by the issue https://issues.apache.org/jira/browse/CASSANDRA-7566.

Unfortunately, when it's a BATCH prepared statement it is not being evicted from the cache. Executing the BATCH statement after a drop of KS/CF, and subsequent recreation of KS/CF with same name, should NOT retrieve them from cache, or else the batch prepared statements will throw an error like java.lang.IllegalArgumentException: Unknown CF fd47fd00-a0d1-11e4-8be2-75ac7e9e28a5 because the statements inside the batch statement still hold a reference to the old (pre-dropping) cf_id.

The attached patch solves this issue.