pillowfight: hide random option

Change-Id: I0b51acf1173f221bbd8438bb0e26ff15381e687e
Reviewed-on: http://review.couchbase.org/42128
Tested-by: Mark Nunberg <mnunberg@haskalah.org>
Reviewed-by: Sergey Avseyev <sergey.avseyev@gmail.com>