CBQE-0: Improved verification to check for outbound mutation on opposite cluster

Change-Id: I716c4d4b0936578cb0d52aa6d8a567d6e9da41fa
Reviewed-on: http://review.couchbase.org/32427
Reviewed-by: Sangharsh Agarwal <sangharsh.agarwal@globallogic.com>
Tested-by: Sangharsh Agarwal <sangharsh.agarwal@globallogic.com>