packaging: setup: clean up jasper artifacts after import

Without this change, _articfacts and _import can in principle be called
with any order, however, since otopi sorts methods by name they'll
always be called in order reverse of intended.

Change-Id: I9e836357771d76e269ff5c582bd7dd525ea30f3a
Signed-off-by: Yedidyah Bar David <didi@redhat.com>