MB-8440: added debug logs for create_connections_test

Change-Id: Ia67ae65e6b2c897b119af0ca8dd8c12d05aeb35e
Reviewed-on: http://review.couchbase.org/26904
Reviewed-by: Andrei Baranouski <andrei.baranouski@gmail.com>
Tested-by: Andrei Baranouski <andrei.baranouski@gmail.com>