CBQE-1242: Errno 32 incremental_rebalance_out_with_mutation_and_deletion

fix [Errno 32] Broken pip incremental_rebalance_out_with_mutation_and_deletion( mixed cluster)
don't use batch for rebalance out 2-1 nodes

Change-Id: I225a813fad04dbd1da9f0f52e05979aa7ef1e532
Reviewed-on: http://review.couchbase.org/25854
Tested-by: buildbot <build@couchbase.com>
Reviewed-by: Andrei Baranouski <andrei.baranouski@gmail.com>