Cancel Running Druid Query when a hive query is cancelled.

https://issues.apache.org/jira/browse/HIVE-20686 ensures that hive query id is passed to druid.
Druid also supports query cancellation by query id.
Queries can be cancelled explicitly using their queryId by sending a DELETE request to following endpoint on the broker or router -

 
DELETE /druid/v2/{queryId}

Implementation wise we need to cancel a druid query when a RecordReader is closed.
I believe Hive should already be calling close on open recordReaders when someone cancels a query.