HPCC-10078 Return 0 graph when calling WUQueryDetails for hthor query

The existing code throws an exception when a WUQueryDetails is called
for non roxie query. It is because the WUQueryDetails trys to get graph
IDs for the query, but, right now, only roxie supports cumulative stats.
This fix returns 0 graph (not exception) if non roxie query is detected.

Signed-off-by: Kevin Wang <kevin.wang@lexisnexis.com>