enhancement(metrics): ddsketch averages are calculated from histogram sum & count fields

[tony-resendiz]

Summary

when histograms are processed by the datadog metrics sink a ddsketch is built by interpolating values from the bucket boundaries. this causes some slight inaccuracy in the sketch average. this change sets the sketch average to the histogram's sum / count.

Vector configuration

[log_schema]
level_key = "status"
level = "info"

[api]
enabled = true
address = "0.0.0.0:8787"
playground = false

[sources.opentelemetry]
type = "opentelemetry"
grpc.address = "0.0.0.0:4317"
http.address = "0.0.0.0:4318"

[sinks.datadog_metrics_sink]
type = "datadog_metrics"
inputs = ["opentelemetry.metrics"]
default_api_key = "${DD_API_KEY}"
endpoint = "https://metrics.agent.datadoghq.com"

How did you test this PR?

built new vector binary and tested against the above config.

Change Type

• Bug fix
• New feature
• Non-functional (chore, refactoring, docs)
• Performance

Is this a breaking change?

• Yes
• No

Does this PR include user facing changes?

• Yes. Please add a changelog fragment based on our guidelines.
• No. A maintainer will apply the no-changelog label to this PR.

References

• Closes: ddsketch from histogram seems inaccurate #24365

Notes

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[github-actions]

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[tony-resendiz]

I have read the CLA Document and I hereby sign the CLA