CBQE-0: add more logs for upgrade tests

Change-Id: Ia3591e64e16287255db6814ef442dd3fdbaf3802
Reviewed-on: http://review.couchbase.org/27080
Reviewed-by: Andrei Baranouski <andrei.baranouski@gmail.com>
Tested-by: Iryna Mironava <irynamironava@yandex.ru>