Fix nodediscover clear for operators

Operators should be allowed to delete discovery data.

confluent_server/confluent/auth.py

@@ -68,6 +68,7 @@ _allowedbyrole = {
             '/nodes/*/shell/sessions*',
         ],
         'delete': [
+            '/discovery/*',
             '/node*/*/events/hardware/log',
         ],
     },