HPCC-8625 Roxie was not handling multiple QuerySet case correctly

If a Roxie had more than one QuerySet associatede with it, only the queries
from the last QuerySet would be accessible.

Also fixes some poor handling of errors if control:queryInfo is given a
queryId that cannot be located.

Signed-off-by: Richard Chapman <rchapman@hpccsystems.com>
Merge pull request #3953 from richardkchapman/roxie-8625

HPCC-8625 Roxie was not handling multiple QuerySet case correctly

Reviewed-by: Gavin Halliday <ghalliday@hpccsystems.com>