MB-100: timely decrease num of items in uprade tests

during the phase of implementation would like to receive the results more often, for regression testing

Change-Id: I3a101894d8e1c2b2fc781b931f264e69348f3dd5
Reviewed-on: http://review.couchbase.org/23651
Reviewed-by: Andrei Baranouski <andrei.baranouski@gmail.com>
Tested-by: Andrei Baranouski <andrei.baranouski@gmail.com>