Update elasticsearch writer to write to datastreams.

[w1ll-i-code]

Is your feature request related to a problem? Please describe.

Creating a new index for each day is no longer considered best practice in elasticsearch. Instead for this kind of timeseries data we want to write to an elasticsearch datastream.

Together with this changes, we also want to update the dataformat of the documents sent to conform to the elasticsearch common schema for easier integration into their existing ecosystem.

Describe the solution you'd like

As discussed with @lippserd, we want to clone the current elasticsearch writer and update it for the new requirements.

[martialblog]

I do agree with using datastreams.

Just a hint, I recently addressed the another issue with the ElasticsearchWriter format here #10511

I provided a small but breaking change here: #10518

If the ElasticsearchDatastreamWriter is introduced, both Writers should use the same format.

[w1ll-i-code]

Hi @martialblog I actually discussed that matter with @lippserd and we decided to move ahead with this implementation to not break the existing implementation (e.g. through a change in data format.) Otherwise we would have overhauled the existing writer.

[martialblog]

@w1ll-i-code I'm all for the datastream implementation, it makes perfect sense. I just want to make sure we get the output format right this time. The index explosion in the current implementation is what is keeping us from using the ESWriter. We should avoid it in the new implementation.