Support using binary Logstash image

To build the Monasca images, they need to be built from source, however,
this doesn't include Logstash. Logstash does not differentiate between
binary or source install types, so we can just use the default.

Partially-Implements: blueprint monasca-roles
Change-Id: I7eb355f25864f2b993780cd2b000c8bcd13f78e8

ansible/roles/monasca/defaults/main.yml

@@ -143,7 +143,7 @@ monasca_log_api_image: "{{ docker_registry ~ '/' if docker_registry else '' }}{{
 monasca_log_api_tag: "{{ monasca_tag }}"
 monasca_log_api_image_full: "{{ monasca_log_api_image }}:{{ monasca_log_api_tag }}"
 
-monasca_logstash_image: "{{ docker_registry ~ '/' if docker_registry else '' }}{{ docker_namespace }}/{{ kolla_base_distro }}-{{ monasca_install_type }}-logstash"
+monasca_logstash_image: "{{ docker_registry ~ '/' if docker_registry else '' }}{{ docker_namespace }}/{{ kolla_base_distro }}-{{ kolla_install_type }}-logstash"
 monasca_logstash_tag: "{{ monasca_tag }}"
 monasca_logstash_image_full: "{{ monasca_logstash_image }}:{{ monasca_logstash_tag }}"