CBLT-332:  turn off DEBUG in set_jenkins_default_param.pl

Change-Id: I74892e5c1c8fe1e0d0d890b234e0d155e71d357e
Reviewed-on: http://review.couchbase.org/41650
Reviewed-by: Philip Labee <philip@couchbase.com>
Tested-by: Philip Labee <philip@couchbase.com>