[prometheusremotewriteexporter] Support conversion of OTel Exponential Histogram to Prometheus Native Histogram

[kovrus]

Description:

Support conversion of OTel Exponential Histogram to Prometheus Native Histogram.

pmetric.ExponentialHistogramDataPoint translates to prompb.Histogram as follows:

• Exp. Scale -> Nat. Schema: histogram is dropped if Scale -4 < and > 8.
  TODO: We can potentially downscale hist to 8 if Scale > 8? (as a separate PR)
• Exp. Count -> Nat. Count: if Flags().NoRecordedValue() is false
• Exp. Sum_ -> Nat. Sum: if it Sum is set and Flags().NoRecordedValue() is false
• Exp. TimeUnixNano -> Nat. Timestamp: TimeUnixNano ns converted Timestamp ms
• Exp. ZeroCount -> Nat. ZeroCount
• Nat. ZeroThreshold is set to the default value 1e-128, once Introduce an optional zero_threshold field to ExponentialHistogramDataPoint opentelemetry-proto#441 is merged, we can use Exp. ZeroThreshold to set the value.
• Exp. Positive -> Nat. PositiveSpans and Nat. PositiveDeltas.
• Exp. Negative -> Nat. NegativeSpans and Nat. NegativeDeltas.
• Exp. Min_ and Max_ are not used.
• Exp. StartTimeUnixNano is not used.

Exp. Exemplars, Labels, and ExponentialHistogramDataPoint will be translated to native hist data structures and will make up one or more prompb.TimeSeries.

Link to tracking Issue:
Resolves #16207

Testing:
Unit tests in pkg/transalator/prometheusremote and exporter/prometheusremotewriteexporter

Documentation:

open-telemetry/opentelemetry-specification#3079

[runforesight]

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build-and-test-windows duration(5 seconds) has decreased 44 minutes 19 seconds compared to main branch avg(44 minutes 24 seconds).

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✅  load-tests workflow has finished in 7 minutes 57 seconds (8 minutes 11 seconds less than main branch avg.) and finished at 10th Jan, 2023.

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[kovrus]

cc: @fstab @gouthamve @codesome

[gouthamve]

cc @jmacd

[gouthamve]

LGTM

[codeboten]

Please rebase and we can get this merged

[kovrus]

@codeboten rebased.

I had to skip the flaky prw exporter TestWALOnExporterRoundTrip test on Linux as well. It was already skipped for Windows, see #10142