CBQE-0: py-autofailover.conf with num items optimizations

reduce num items for 3 buckets

cluster is overloaded in this case http://qa.hq.northscale.net/job/centos_x64--03_01--failover_tests-P0/19/consoleFull

Change-Id: I0fc6002b0856f83bc33b66369949fd0d0d573977
Reviewed-on: http://review.couchbase.org/35064
Reviewed-by: Andrei Baranouski <andrei.baranouski@gmail.com>
Tested-by: Andrei Baranouski <andrei.baranouski@gmail.com>