fix(tests): Remove listenerClass field, which was (somewhat) removed (#409)

Author: sbernauer

tests/templates/kuttl/kerberos-hdfs/30-install-hdfs.yaml.j2

@@ -14,7 +14,6 @@ commands:
             productVersion: "{{ test_scenario['values']['hdfs-latest'] }}"
             pullPolicy: IfNotPresent
           clusterConfig:
-            listenerClass: external-unstable
             dfsReplication: 1
             authentication:
               tlsSecretClass: tls