We were creating the cloned triggers with an empty list of arguments,
losing the ones that had been specified by the user when creating the
trigger in the partitioned table.  Repair.

This was forgotten in commit 86f57594.

Author: Patrick McHardy
Reviewed-by: Tomas Vondra
Discussion: https://postgr.es/m/20190709130027.amr2cavjvo7rdvac@access1.trash.net
Discussion: https://postgr.es/m/15752-123bc90287986de4@postgresql.org