MB-11888: handle missing https ports in old-style bucket details

Otherwise go-couchbase fails to parse undefineds in ports attribute.

Change-Id: Ice9a0df0e85312007aee2d7ac84e9ab1869e89da
Reviewed-on: http://review.couchbase.org/40484
Tested-by: Aliaksey Kandratsenka <alkondratenko@gmail.com>
Reviewed-by: Aliaksey Kandratsenka <alkondratenko@gmail.com>