Merge pull request #53766 from liggitt/ui-redirect

Automatic merge from submit-queue. If you want to cherry-pick this change to another branch, please follow the instructions <a href="https://github.com/kubernetes/community/blob/master/contributors/devel/cherry-picks.md">here</a>.

Remove /ui/ redirect

The existing kube-apiserver hard-codes `/ui` to redirect to an optional add-on, which is not appropriate. It does not work in the following scenarios:
* https-enabled dashboards
* the dashboard is deployed to a different namespace or service name
* the dashboard is not installed at all
* authorization is enabled and does not allow access to /ui

This PR removes the hard-coded `/ui` redirect.

```release-note
apiserver: the /ui kube-dashboard redirect has been removed. Follow instructions specific to your deployment to access kube-dashboard
```

hack/make-rules/test-cmd-util.sh

@@ -3503,10 +3503,8 @@ run_kubectl_local_proxy_tests() {
 
   kube::log::status "Testing kubectl local proxy"
 
-  # Make sure the UI can be proxied
   start-proxy
-  check-curl-proxy-code /ui 307
-  check-curl-proxy-code /api/ui 404
+  check-curl-proxy-code /api/kubernetes 404
   check-curl-proxy-code /api/v1/namespaces 200
   if kube::test::if_supports_resource "${metrics}" ; then
     check-curl-proxy-code /metrics 200
@@ -3524,7 +3522,8 @@ run_kubectl_local_proxy_tests() {
 
   # Custom paths let you see everything.
   start-proxy /custom
-  check-curl-proxy-code /custom/ui 307
+  check-curl-proxy-code /custom/api/kubernetes 404
+  check-curl-proxy-code /custom/api/v1/namespaces 200
   if kube::test::if_supports_resource "${metrics}" ; then
     check-curl-proxy-code /custom/metrics 200
   fi