JDBCStringBasedStore should disable auto commit for publish methods

Some JDBC drivers do not do paging for result sets when auto commit is enabled, namely postgresql

https://jdbc.postgresql.org/documentation/83/query.html#query-with-cursor

There shouldn't be any drawbacks of disabling auto commit before performing the query. We wouldn't even need to rollback/commit the connection and just return it to the pool. The pool can do that for us as we don't care if it is committed as it is a read only query.

Could you please give the opportunity to disable autoCommit in order for the JDBC page size to work (even if the store is not transactional).

Otherwise, fetch size is ignore and postgresql just pulls in the entire select.

Thanks
--nick