Optimize ElasticSearch indices later.

* modules/openstack_project/manifests/elasticsearch.pp: Run the index
optimize cron 8 hours later to avoid optimizing an index that is still
in use. Doing this as during periods of high test load (eg around
milestones) logstash may not be able to index all of the previous day's
logs prior to 0500 of the next day.

Change-Id: Ic00413bea6863e0fc945b5507be7b4a2aaaea3af
Merge "Optimize ElasticSearch indices later."