CBQE-0: add logs for upgrade test

Change-Id: I94676ae9e4163063201e9b507a6fbe35248ad538
Reviewed-on: http://review.couchbase.org/27064
Tested-by: buildbot <build@couchbase.com>
Reviewed-by: Iryna Mironava <irynamironava@yandex.ru>