CBLT-332:  turn on DEBUG in set_jenkins_default_param.pl

Change-Id: I3688deaab21dfb14de9518d9d6774a324eaae9a9
Reviewed-on: http://review.couchbase.org/41626
Reviewed-by: Philip Labee <philip@couchbase.com>
Tested-by: Philip Labee <philip@couchbase.com>