[BP to 6.0.4] rpm -U should automatically shutdown and startup couchbase during couchbase

For upgrade to MH, the upgrade script should automatically stop the couchbase-server before starting upgrade, and should bring up the server once the upgrade process is done. Currently, it does not stop, but does detect that the couchbase server is running. It would eliminate user errors if stopping of server is also automated. See MB-35419 for such an issue.

Also, the command shown for stopping couchbase server is incorrect for centos7 and lot of other platforms.
Couchbase should not be running.
Please use: /etc/init.d/couchbase-server stop

Needless to say, this applies to all supported platforms.