Fixes dev/setup-rancher-clusters

Fixes dev/setup-rancher-clusters where `public_hostname` may end up
being without IP address.

E.g.

```
+ upstream_ctx=k3d-upstream
+ downstream_ctx=k3d-downstream1
+ rancherpassword=rancherpassword
+ public_hostname=
+ '[' -z '' ']'
+ kubectl get service -n kube-system traefik -o 'jsonpath={.status.loadBalancer.ingress[0].ip}'
Error from server (NotFound): services "traefik" not found
+ sleep 3
+ kubectl get service -n kube-system traefik -o 'jsonpath={.status.loadBalancer.ingress[0].ip}'
Error from server (NotFound): services "traefik" not found
+ sleep 3
+ kubectl get service -n kube-system traefik -o 'jsonpath={.status.loadBalancer.ingress[0].ip}'
Error from server (NotFound): services "traefik" not found
+ sleep 3
+ kubectl get service -n kube-system traefik -o 'jsonpath={.status.loadBalancer.ingress[0].ip}'
++ kubectl get service -n kube-system traefik -o 'jsonpath={.status.loadBalancer.ingress[0].ip}'
+ ip=
+ public_hostname=.sslip.io
```

Author: p-se

dev/setup-rancher-clusters

@@ -19,8 +19,13 @@ rancherpassword="${RANCHER_PASSWORD-rancherpassword}"
 
 public_hostname="${public_hostname:-}"
 if [ -z "${public_hostname}" ]; then
-  until kubectl get service -n kube-system traefik -o jsonpath='{.status.loadBalancer.ingress[0].ip}'; do sleep 3; done
-  ip=$(kubectl get service -n kube-system traefik -o jsonpath='{.status.loadBalancer.ingress[0].ip}')
+  success=-1
+  until [ "$success" -eq 0 ]; do
+    echo "Waiting for Traefik LoadBalancer IP..."
+    sleep 5
+    ip=$(kubectl get service -n kube-system traefik -o jsonpath='{.status.loadBalancer.ingress[0].ip}')
+    success=$?
+  done
   public_hostname="$ip.sslip.io"
 fi