Refactor memcached_servers

This patch aims to add a prefix for memcached_server
on each role to give the ability for deployers to
override the location of memcached cluster. I.e users
wants to create a single memcached cluster with k8s
for each service.

We also add pymemcache based on [1]

[1] https://review.opendev.org/711429

Change-Id: I57796a7e6d99fc40af0647b3004fed95ce9f298f

defaults/main.yml

@@ -52,6 +52,7 @@ murano_pip_packages:
   - murano
   - PyMySQL
   - python-memcached
+  - pymemcache
   - systemd-python
 murano_optional_oslomsg_amqp1_pip_packages:
   - oslo.messaging[amqp1]
@@ -60,6 +61,8 @@ murano_bin: "{{ _murano_bin }}"
 
 murano_pip_install_args: "{{ pip_install_options | default('') }}"
 
+murano_memcached_servers: "{{ memcached_servers }}"
+
 # Services
 murano_services:
   murano-api:

templates/murano.conf.j2

@@ -17,7 +17,7 @@ auth_url = {{ keystone_service_adminurl }}
 identity_uri = {{ keystone_service_adminuri }}
 insecure = {{ keystone_service_publicuri_insecure | bool }}
 
-memcached_servers = {{ memcached_servers }}
+memcached_servers = {{ murano_memcached_servers }}
 # if your memcached server is shared, use these settings to avoid cache poisoning
 memcache_security_strategy = ENCRYPT
 memcache_secret_key = {{ memcached_encryption_key }}