Improve logging of sync services

{"severity":"INFO","time":"2019-07-26T00:32:25.645Z","correlation_id":"0c34fa7f-0730-4ccd-8054-bdbd19790224","class":"Geo::FileDownloadDispatchWorker","message":"Finished scheduler","job_id":"1691016f2dd940f2ce34311e","total_loops":0,"duration":0.081166261,"reason":"complete"}

To investigate some production problems easier I think we need to have more attributes here like:

• ✅ host - This would be a unique host/node name that will apply to all Geo log entries

☝ implemented in !21171 (closed)

• trigger_type - With valid values being backfill or event
• event_id - If trigger_type == event then include the event ID.