Fix check external_openstack_tenant_name value (#6270)

We need to specify either external_openstack_tenant_name or
external_openstack_tenant_id. Those values were checked by seeing they
are defined or they have actual values separately.
However those values are always defined because of the following code
of openstack/defaults/main.yml:

external_openstack_tenant_id: "{{ lookup('env','OS_TENANT_ID')| default(lookup('env','OS_PROJECT_ID'),true) }}"
external_openstack_tenant_name: "{{ lookup('env','OS_TENANT_NAME')| default(lookup('env','OS_PROJECT_NAME'),true) }}"

So even if not specifying both values, those checks could not detect
the misconfiguration. This fixes this to detect the misconfiguration.

roles/kubernetes-apps/external_cloud_controller/openstack/tasks/openstack-credential-check.yml

@@ -23,12 +23,5 @@
   fail:
     msg: "one of external_openstack_tenant_id or external_openstack_tenant_name must be specified"
   when:
-    - external_openstack_tenant_id is not defined or not external_openstack_tenant_id
-    - external_openstack_tenant_name is not defined
-
-- name: External OpenStack Cloud Controller | check external_openstack_tenant_name value
-  fail:
-    msg: "one of external_openstack_tenant_id or external_openstack_tenant_name must be specified"
-  when:
-    - external_openstack_tenant_name is not defined or not external_openstack_tenant_name
-    - external_openstack_tenant_id is not defined
+    - (external_openstack_tenant_id is not defined or not external_openstack_tenant_id) and
+      (external_openstack_tenant_name is not defined or not external_openstack_tenant_name)