zabbix-agent: Fix agent server on apollo

Signed-off-by: Florian Pritz <bluewind@xinu.at>

playbooks/apollo.yml

@@ -32,4 +32,4 @@
     - { role: patchwork, tags: ["patchwork"] }
     - { role: kanboard, tags: ["kanboard"] }
     - { role: zabbix-server, tags: ["zabbix", "zabbix-server"] }
-    - { role: zabbix-agent, tags: ["zabbix", "zabbix-agent"] }
+    - { role: zabbix-agent, zabbix_agent_server: "127.0.0.1", tags: ["zabbix", "zabbix-agent"] }

roles/zabbix-agent/defaults/main.yml

+---
+zabbix_agent_server: zabbix.archlinux.org

roles/zabbix-agent/templates/zabbix_agentd.conf

 LogType=system
-Server=zabbix.archlinux.org
-ServerActive=zabbix.archlinux.org
+Server={{zabbix_agent_server}}
+ServerActive={{zabbix_agent_server}}
 Hostname={{ansible_hostname|lower}}
 #Include=/etc/zabbix/zabbix_agentd.conf.d/*.conf