Fix $hostinterfaceitem to not be an Fqdn.

As per the upstream documentation
(https://www.zabbix.com/documentation/5.0/manual/appendix/config/zabbix_agentd),
hostinterfaceitem should be a Zabbix item and NOT an FQDN.

Closes #725

Author: Braxton Schafer

manifests/agent.pp

@@ -275,7 +275,7 @@
   $hostmetadata                                   = $zabbix::params::agent_hostmetadata,
   $hostmetadataitem                               = $zabbix::params::agent_hostmetadataitem,
   Optional[Stdlib::Fqdn] $hostinterface           = $zabbix::params::agent_hostinterface,
-  Optional[Stdlib::Fqdn] $hostinterfaceitem       = $zabbix::params::agent_hostinterfaceitem,
+  $hostinterfaceitem                              = $zabbix::params::agent_hostinterfaceitem,
   $refreshactivechecks                            = $zabbix::params::agent_refreshactivechecks,
   $buffersend                                     = $zabbix::params::agent_buffersend,
   $buffersize                                     = $zabbix::params::agent_buffersize,