We put the doas authorization for collectd in the global file and we let it if
collectd is not there, because otherwise the authorization would be removed if
the base role was run without the collectd role, even if collectd was still
running. Collectd would have been broken.
This variable had to be activated only if collectd_plugin_exec_ifq_drops or
collectd_plugin_exec_dns_stats was also activated, for some configuration to be
taken into account. I changed the role so that the configuration is
automatically taken into account if one of these two variables is activated.