{174996173}: Workaround for remote-insert that reads from the same remote

[riverszhang89]

Dorin pointed out the bug, that if a query reads from a remote table and inserts the results into another table in the same remote database, the query will hang (e.g., INSERT INTO remote.t1 SELECT * FROM remote.t2).

This patch works it around by always using a temptable plan for such a query.