Don't duplicate planning logic in citus' explain hook.
Don't duplicate planning logic in citus' explain hook.

Instead use pg_plan_query() like the normal explain does, and use that
to explain the query.  That's important because it allows to remove
the duplicated planner logic from multi_explain - and that logic is
about to get more complicated.

citusdata/citus,citusdata/citus,citusdata/citus,citusdata/citus,citusdata/citus