Use Elasticsearch auto-generated ids for performance

[gigsda]

this option is for someone who need better indexing performance but not need 'exactly once'

https://www.elastic.co/guide/en/elasticsearch/reference/master/tune-for-indexing-speed.html#_use_auto_generated_ids

[ghost]

@confluentinc It looks like @gigsda just signed our Contributor License Agreement. :+1:

Always at your service,

clabot

[cla-assistant[bot]]

Thank you for your submission! We really appreciate it. Like many open source projects, we ask that you all sign our Contributor License Agreement before we can accept your contribution.
0 out of 2 committers have signed the CLA.

:x: gigsda
:x: wonkuk-yang
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