CBQE-0: py-newrebalance.conf with diff value_size param

Change-Id: Iba3f8cb75c8998ba31d59a89880a6bc30481eff6
Reviewed-on: http://review.couchbase.org/25753
Tested-by: buildbot <build@couchbase.com>
Reviewed-by: Ketaki Gangal <ketakigangal@gmail.com>