UI: Revert to the original approach for response time

Author: jedisct1

dnscrypt-proxy/monitoring_ui.go

@@ -306,13 +306,7 @@ func (ui *MonitoringUI) UpdateMetrics(pluginsState PluginsState, msg *dns.Msg, s
 	}
 
 	// Update response time - back to counters lock
-	var responseTime int64
-	if !pluginsState.requestStart.IsZero() && !pluginsState.requestEnd.IsZero() {
-		responseTime = pluginsState.requestEnd.Sub(pluginsState.requestStart).Milliseconds()
-	} else {
-		// For incomplete queries, use timeout duration
-		responseTime = pluginsState.timeout.Milliseconds()
-	}
+	responseTime := time.Since(start).Milliseconds()
 
 	// Cap at timeout to handle system sleep/suspend
 	maxResponseTime := pluginsState.timeout.Milliseconds()