CBQE-2364: fixing test xdcr.xdcrMiscTests.test_verify_mb8825 to add stats from all the nodes for comparison instead of master nodes

Change-Id: Ic29b8a14fcdb900ad9e976272d6a697413a6f5ab
Reviewed-on: http://review.couchbase.org/40232
Tested-by: buildbot <build@couchbase.com>
Reviewed-by: Sangharsh Agarwal <sangharsh.agarwal@globallogic.com>
Tested-by: Sangharsh Agarwal <sangharsh.agarwal@globallogic.com>