fix: Correct Flux UI pod selector labels to match deployed weave-gitops labels

Actual labels are app.kubernetes.io/name=weave-gitops and
app.kubernetes.io/instance=flux-system-weave-gitops.

infrastructure/addons/flux-ui/flux-tailscale-service.yaml

@@ -10,8 +10,8 @@ spec:
   type: LoadBalancer
   loadBalancerClass: tailscale
   selector:
-    app.kubernetes.io/name: gitops-server
-    app.kubernetes.io/instance: weave-gitops
+    app.kubernetes.io/name: weave-gitops
+    app.kubernetes.io/instance: flux-system-weave-gitops
   ports:
     - name: http
       port: 9001