CBQE-1735: upgradeXdcr offline upgrade test fix for not rebalance out
master node

Change-Id: I197d1fb6ba55d00dd1aba9b3a1cdb28a571a854c
Reviewed-on: http://review.couchbase.org/30861
Reviewed-by: Iryna Mironava <irynamironava@yandex.ru>
Reviewed-by: Sangharsh Agarwal <sangharsh.agarwal@globallogic.com>
Tested-by: Sangharsh Agarwal <sangharsh.agarwal@globallogic.com>