use bulk ES operations and local cache to increase the processing throughput of the microservice

[konstan]

The initial implementation was done with strict (as much as possible) consistency guarantees. However, with ~25 telemetry sets per second (from 525 NEs with 30-sec intervals) and with the subscription on network-rx/tx, disk, load, on/off -- the throughput of the implementation wasn't able to catch up and was starting to create a backlog.

Solution: trade the consistency for throughput and implement local cache and bulk ES operations. Downside: in case of backlog (not due to the service), the multiple instances of the service may create a race condition.