Update glance_store variables

Some variables were deprecated in rocky and marked for removal in Ussuri
We do replace them not to have things broken afterwards.

Change-Id: I75d2e3631b0dfebb72efd946fd61252bb9b766b0
Related-Bug: #1846052

defaults/main.yml

@@ -77,6 +77,10 @@ glance_system_user_home: "/var/lib/{{ glance_system_user_name }}"
 
 glance_registry_host: "{{ internal_lb_vip_address }}"
 glance_default_store: file
+# For support of multiple backends provide `glance_additional_stores` in the format:
+# glance_additional_stores:
+#   - name: private_store
+#     type: http
 glance_additional_stores:
   - http
   - cinder

templates/glance-api.conf.j2

@@ -34,6 +34,10 @@ image_cache_dir = {{ glance_system_user_home }}/cache/
 show_image_direct_url = {{ glance_show_image_direct_url }}
 show_multiple_locations = {{ glance_show_multiple_locations }}
 
+{% set glance_available_stores = [ glance_default_store ] + glance_additional_stores %}
+enabled_backends = {% for backend in glance_available_stores %}{{ ('name' in backend) | ternary(backend['name'], backend) }}:{{ ('type' in backend) | ternary(backend['type'], backend) }}{% if not loop.last %},{% endif %}{% endfor %}
+
+
 [task]
 task_executor = {{ glance_task_executor }}
 
@@ -78,10 +82,7 @@ transport_url = {{ glance_oslomsg_notify_transport }}://{% for host in glance_os
 flavor = {{ glance_flavor }}
 
 [glance_store]
-default_store = {{ glance_default_store }}
-
-{% set glance_available_stores = [ glance_default_store ] + glance_additional_stores %}
-stores = {% for backend in glance_available_stores %}{{ backend }}{% if not loop.last %},{% endif %}{% endfor %}
+default_backend = {{ glance_default_store }}
 
 {% if 'file' in glance_available_stores %}
 filesystem_store_datadir = {{ glance_system_user_home }}/{{ glance_nfs_local_directory }}/