[exporter/elasticsearch] remove dedup config

[axw]

Description:

Remove the dedup configuration setting, and always de-duplicate. Elasticsearch does not permit duplicate keys in JSON objects, and this configuration is adding more complexity to the code than it's worth.

I've simplified the internal/objmodel API slightly, unexporting the Sort methods, which are internally called by the now unconditional call to Dedup.

Link to tracking Issue:

Closes #33773

Testing:

Ran the unit tests, which cover deduplication. None of the tests in package elasticsearchexporter covered dedup: false.

Documentation:

[andrzej-stencel]

@axw Can you split the dedot change into a separate PR please?

[axw]

@andrzej-stencel I've opened #33779 and #33780 for just the deprecations. I'll mark this one as draft and reopen it after those deprecations are released.

[carsonip]

one nit otherwise lgtm

[andrzej-stencel]

According to the docs:

the option (...) MAY be removed after N+2 or 6 months, whichever comes later

I believe this means we should not remove this option before January 2025 (six months after v0.104.0). We can hide the option behind a feature flag if it helps (not sure if it makes sense in this case?).

You can still make the feature non-operational according to this:

the option MAY be made non operational already by the same version where it is deprecated

[axw]

@andrzej-stencel thanks for pointing out the docs. I've reinstated the config, but made it a no-op. I didn't add it back into the README though - let me know if you disagree with that.

the option and the WARN level message MAY be removed after N+2 or 6 months, whichever comes later

I find the "MAY" in this to be a little bit ambiguous. Perhaps it would be worth rewording to:

"the option and WARN level message MUST NOT be removed earlier than N+2 o 6 months, whichever comes later"

WDYT?

[andrzej-stencel]

I didn't add it back into the README though - let me know if you disagree with that.

I think if the option exists, it should be described in the README - saying it is deprecated and non-functional.

I find the "MAY" in this to be a little bit ambiguous. Perhaps it would be worth rewording to:
"the option and WARN level message MUST NOT be removed earlier than N+2 o 6 months, whichever comes later"

I agree that the wording might be a bit misleading. Your proposal seems OK, please send a PR to update the wording, let's see what other maintainers think.