the kubeconfig doesn't work from UI download

[huxiaoliang]

The imported cluster kubeconfig file down load from UI doesn't work due to below error message:

root@VM-0-77-ubuntu:~#  kubectl --kubeconfig ./download.kubeconfig get node                         
Error in configuration: context was not found for specified context: cls-7rjdxr9q-default

to workaround: remove context string as belows

root@VM-0-77-ubuntu:~# diff -u download3.kubeconfig download2.kubeconfig   
--- download3.kubeconfig        2021-01-30 20:10:35.698889729 +0800
+++ download2.kubeconfig        2021-01-30 20:07:07.791429404 +0800
@@ -8,7 +8,7 @@
 - context:
     cluster: cls-7rjdxr9q
     user: cls-7rjdxr9q-admin
-  name: cls-7rjdxr9q-context-default
+  name: cls-7rjdxr9q-default
 current-context: cls-7rjdxr9q-default
 kind: Config
 preferences: {}
root@VM-0-77-ubuntu:~#