Don't specify "ExecReload" command in systemd unit

The "reload_config" command doesn't work the way admins would typically
expect, so it shouldn't be exposed via systemd.  Those who understand
the behavior can execute the command using ejabberdctl.

ejabberd.service.template

@@ -11,7 +11,6 @@ Restart=on-failure
 RestartSec=5
 ExecStart=@ctlscriptpath@/ejabberdctl start
 ExecStop=@ctlscriptpath@/ejabberdctl stop
-ExecReload=@ctlscriptpath@/ejabberdctl reload_config
 PrivateDevices=true
 ProtectSystem=full