memcached_servers is miswrited to memcache_servers

[James Du]

memcached_servers is miswrited to memcache_servers.
For example:
In kolla\ansible\roles\sahara\templates\sahara.conf.j2:
{% if orchestration_engine == 'KUBERNETES' %}
memcache_servers = {{ memcached_servers }} ------ this is wrong.
{% else %}
memcached_servers = {% for host in groups['memcached'] %}{{ hostvars[host]['ansible_' + hostvars[host]['api_interface']]['ipv4']['address'] }}:{{ memcached_port }}{% if not loop.last %},{% endif %}{% endfor %} -------this is right
{% endif %}

[Jeffrey Zhang (jeffrey4l)]

in kolla-kubernetes, the memcached_servers is configured to `memcached_servers: "memcached"`, and in ansible deployment, this is not used, so i think this is OK.

[OpenStack Infra (hudson-openstack)]

Change abandoned by dupengfei (<email address hidden>) on branch: master
Review: https://review.openstack.org/393088
Reason: timeout