Be consistent with memcached group name

Without this patch, two different groups are used for memcached:
"memcached" and "memcached_all".

This is a problem if you want to deploy openstack-ansible with a
static inventory, and only define one of the groups "memcached".
You would define the group "memcached" because it is already the
one used in the group_vars, and it makes more sense as there is
only a single component in "memcached" (unlike nova, cinder, ...).

This patches solves the problem by ensuring the only group used
for memcached is named "memcached" and not "memcached_all".

Change-Id: Ie7ff9a33df8d0eabdee8307a4f8ef5694c72bdd9

inventory/group_vars/all/infra.yml

@@ -34,7 +34,7 @@ galera_root_user: "root"
 memcached_port: 11211
 memcached_servers: >-
   {{
-    (groups['memcached_all'] | map('extract', hostvars, 'ansible_host') | list)
+    (groups['memcached'] | map('extract', hostvars, 'ansible_host') | list)
       | map('regex_replace', '(.*)' ,'\\1:' ~ memcached_port)
       | list
       | join(',')

scripts/upgrade-utilities/playbooks/memcached-flush.yml

@@ -14,7 +14,7 @@
 # limitations under the License.
 
 - name: Memcached cache flush
-  hosts: memcached_all
+  hosts: memcached
   gather_facts: true
   user: root
   vars: