cleanup: Remove expired ports:
2022-02-28 net-mgmt/zabbix3-proxy: Upstream EOL reached on 2021-02-28
2022-02-28 net-mgmt/zabbix3-java: Upstream EOL reached on 2021-02-28
2022-02-28 net-mgmt/zabbix3-frontend: Upstream EOL reached on 2021-02-28
2022-02-28 net-mgmt/zabbix3-agent: Upstream EOL reached on 2021-02-28
2022-02-28 net-mgmt/zabbix3-server: Upstream EOL reached on 2021-02-28