CBQE-1220 update conf file for warmup test

Change-Id: I30e72515edc65ad1b110606b1e432d796172d6f3
Reviewed-on: http://review.couchbase.org/26053
Reviewed-by: Chisheng Hong <chisheng@couchbase.com>
Tested-by: Chisheng Hong <chisheng@couchbase.com>