Don't specify a docker registry when kolla_docker_registry is defined but None

This is the default.

ansible/container-image-build.yml

@@ -38,7 +38,9 @@
         username: "{{ kolla_docker_registry_username }}"
         password: "{{ kolla_docker_registry_password }}"
         reauthorize: yes
-      when: kolla_docker_registry_username is not none and kolla_docker_registry_password is not none
+      when:
+        - kolla_docker_registry_username is not none
+        - kolla_docker_registry_password is not none
 
     - name: Ensure Kolla container images are built
       shell: >
@@ -47,7 +49,7 @@
         kolla-build \
         --config-dir {{ kolla_build_config_path }} \
         {% if item.type is defined %}--type {{ item.type }}{% endif %} \
-        {% if kolla_docker_registry != "" and kolla_docker_registry != None %}--registry {{ kolla_docker_registry }}{% endif %} \
+        {% if kolla_docker_registry is not none %}--registry {{ kolla_docker_registry }}{% endif %} \
         {% if push_images | bool %}--push{% endif %} \
         {{ item.regexes }} 2>&1 | tee --append {{ kolla_build_log_path }}
       with_items: "{{ container_image_sets }}"