For an unsharded search collection, when $unionWith is run with $search as the first stage of the subpipeline, we fail a tassert that we were only expecting one cursor.

This is because we run PSS as we are on a sharded cluster (this seems to be the case on 6.0 and potentially 7.0) and we then later include the protocolVersion when querying mongot, causing it to return two cursors. We then fail a tassert as we were only expecting one cursor.