[system test] offline upgrade should stop if detect ip and ip_start files do not contain hostname

Offline upgrade from 2.0.0 to 2.0.1 using host name.
The upgrade process failed to retain configuration from 2.0.0 cluster due to user does not update hostname in ip and ip_start files at /opt/couchbase/var/lib/couchbase/
If couchbase server uses hostname and want to do offline upgrade (detect in couchbase-server file with -name), offline upgrade process should ask user if they update hostname in ip and ip_start files with hostname and give option yes or stop the offline upgrade.