Reload Zabbix proxy configuration cache

When an active proxy is told to reload its configuration cache, it connects to the server, gets the new configuration data, and then updates the local cache:

sudo zabbix_proxy -R config_cache_reload

Runtime commands depend on the PID file being properly configured. When you run the previous command, it looks for the PidFile option in the default proxy configuration file, looks up the PID from the PID file, and sends the signal to that process.