Set searchlight-api workers using openstack_service_workers

Change-Id: I8b9c8b374fa35f97876f27f1a50a3b188ce9dae0
Closes-Bug: #1671739

ansible/roles/searchlight/templates/searchlight.conf.j2

@@ -10,6 +10,7 @@ transport_url = rabbit://{% for host in groups['rabbitmq'] %}{{ rabbitmq_user }}
 port = {{ searchlight_api_port }}
 bind_host = {{ hostvars[inventory_hostname]['ansible_' + api_interface]['ipv4']['address'] }}
 public_endpoint = {{ public_protocol }}://{{ kolla_external_fqdn }}:{{ searchlight_api_port }}
+workers = {{ openstack_service_workers }}
 
 [elasticsearch]
 hosts = {{ searchlight_elasticsearch_url }}