Update server.py: Rename the default context to test as suggested...

Update server.py: Rename the default context to test as suggested [here](https://git.webis.de/code-generic/code-admin-knowledgebase/issues/81#note_3426).

tools/k8s/openid-app/server.py

@@ -190,10 +190,10 @@ CMDLINE_TEMPLATE = """\
         --server=https://betaweb001.medien.uni-weimar.de:6443 \\
         --insecure-skip-tls-verify=true
 
-    kubectl config set-context webis6 --cluster=webis6 --user="{u}"
+    kubectl config set-context test --cluster=webis6 --user="{u}"
     kubectl config set-context betaweb --cluster=betaweb --user="{u}"
 
-    kubectl config use-context webis6
+    kubectl config use-context test
 }}
 """