Build logstash when monasca is enabled

logstash is required for monasca log transformer

Change-Id: I8da3f80b9bc928997fe087b5abe893a867d46aa8

ansible/group_vars/all/kolla

@@ -164,6 +164,8 @@ overcloud_container_image_regex_map:
     enabled: "{{ kolla_enable_kibana | bool }}"
   - regex: kolla-toolbox
     enabled: True
+  - regex: logstash
+    enabled: "{{ kolla_enable_monasca | bool }}"
   - regex: magnum
     enabled: "{{ kolla_enable_magnum | bool }}"
   - regex: manila