[DOC OCP] Generic listeners with random name - InvalidHost

If we specify different name from external, in this case, it is external1 the route can not be created
```
oc get route
NAME HOST/PORT PATH SERVICES PORT TERMINATION WILDCARD
my-cluster-kafka-external1-0 my-cluster-kafka-external1-0-multiple-listeners-cluster-test.10.37.144.26.nip.io my-cluster-kafka-external1-0 8091 passthrough None
my-cluster-kafka-external1-1 my-cluster-kafka-external1-1-multiple-listeners-cluster-test.10.37.144.26.nip.io my-cluster-kafka-external1-1 8091 passthrough None
my-cluster-kafka-external1-2 my-cluster-kafka-external1-2-multiple-listeners-cluster-test.10.37.144.26.nip.io my-cluster-kafka-external1-2 8091 passthrough None
my-cluster-kafka-external1-bootstrap InvalidHost my-cluster-kafka-external1-bootstrap 8091 passthrough None
```
The route DNS is not created.