zabbix: remove server variant

[ryandesign (Ryan Carsten Schmidt)]

The zabbix port has a server variant which says:

variant server  \
    description {Dummy variant} {
# This variant doesn't do anything in this port.  Its only purpose is to trigger the server
# variant in the mysql5 port.
}

Since the mysql5 port doesn't have a server variant anymore, this variant now serves no purpose in the zabbix port and should be removed.

[ryandesign (Ryan Carsten Schmidt)]

The post-install instructions also talk to the user about the mysql5 port's +server variant. This is now the mysql5-server port. But really it's not the business of the zabbix port to tell the user how to set up a MySQL server; that's the business of the mysql5-server port, or the wiki.

[markd@…]

Fixed in #62583. Thanks. I'm not convinced that it is not the business of a ui_msg to tell the user anything a port author deems expedient to communicate, but it is a mute point now and unnecessary.

[markd@…]

r62583.