When a query has a filter that only needs to be evaluated once per
query it will be represented as a Result node with the filter
condition on the Result node and the actual query as child of the
result node. find_data_node_scan_state_child did not consider
Result node as valid node to contain a DataNodeScan node leading
to a `unexpected child node of Append or MergeAppend: 62` for
queries that had one-time filter with a subquery.
