Reduce the prefetch of Khronos to 6

Author: Nathan219

ansible/group_vars/alpha-khronos.yml

@@ -42,7 +42,7 @@ container_envs: >
   -e INTERCOM_APP_ID={{ intercom_app_id | default('undefined') }}
   -e KHRONOS_MAVIS=http://{{ mavis_hostname }}
   -e KHRONOS_MONGO=mongodb://{{ khronos_mongo_auth }}@{{ mongo_hosts }}/{{ khronos_mongo_database }}
-  -e KHRONOS_PREFETCH=100
+  -e KHRONOS_PREFETCH=6
   -e LOG_LEVEL=error
   {% if node_env != "production-epsilon" %}
     -e MONGO_CACERT=/opt/ssl/mongo-client/ca.pem