Hotfix for demo url for backend (#1931)

### What's done:
 * Added demo url to backend-configmap.yaml (http://demo:5421 -> http://demo)

Author: sanyavertolet

save-cloud-charts/save-cloud/templates/backend-configmap.yaml

@@ -6,6 +6,7 @@ data:
   application.properties: |
     backend.preprocessor-url=http://preprocessor
     backend.orchestrator-url=http://orchestrator
+    backend.demo-url=http://demo
     backend.loki.url=http://loki:3100
     backend.loki.labels.agent-container-name=pod
     backend.loki.labels.application-name=app