Removing authentication from the /ping route to match influxdb (influ…

…xdata#5316)

plugins/inputs/influxdb_listener/http_listener.go

@@ -229,9 +229,7 @@ func (h *HTTPListener) ServeHTTP(res http.ResponseWriter, req *http.Request) {
 		h.PingsRecv.Incr(1)
 		defer h.PingsServed.Incr(1)
 		// respond to ping requests
-		h.AuthenticateIfSet(func(res http.ResponseWriter, req *http.Request) {
-			res.WriteHeader(http.StatusNoContent)
-		}, res, req)
+		res.WriteHeader(http.StatusNoContent)
 	default:
 		defer h.NotFoundsServed.Incr(1)
 		// Don't know how to respond to calls to other endpoints