feat(datadogexporter): adds remap_metrics feature gate (open-telemetry#35025)

**Description:** <Describe what has changed.>

Adds a metrics configuration that enables/disables the conversion of
OpenTelemetry metrics to Datadog semantics in the Datadog Exporter. This
conversion will soon occur in a datadog semantic processor.

**Link to tracking Issue:** N/A

**Testing:** Unit tests

*̶*̶D̶o̶c̶u̶m̶e̶n̶t̶a̶t̶i̶o̶n̶:̶*̶*̶ O̶n̶c̶e̶ t̶h̶i̶s̶
c̶o̶n̶f̶i̶g̶u̶r̶a̶t̶i̶o̶n̶ i̶s̶ G̶A̶ w̶e̶ w̶i̶l̶l̶ u̶p̶d̶a̶t̶e̶ t̶h̶e̶
d̶o̶c̶s̶ h̶e̶r̶e̶:̶
h̶t̶t̶p̶s̶:̶//d̶o̶c̶s̶.d̶a̶t̶a̶d̶o̶g̶h̶q̶.c̶o̶m̶/o̶p̶e̶n̶t̶e̶l̶e̶m̶e̶t̶r̶y̶/c̶o̶l̶l̶e̶c̶t̶o̶r̶_̶e̶x̶p̶o̶r̶t̶e̶r̶/c̶o̶n̶f̶i̶g̶u̶r̶a̶t̶i̶o̶n̶/

---------

Co-authored-by: Yang Song <[email protected]>
Co-authored-by: Pablo Baeyens <[email protected]>

Author: 3 people

.chloggen/munir_add-option-to-avoid-remapping.yaml

@@ -0,0 +1,13 @@
+change_type: enhancement 
+
+# The name of the component, or a single word describing the area of concern, (e.g. filelogreceiver)
+component: datadogexporter
+
+# A brief description of the change.  Surround your text with quotes ("") if it needs to start with a backtick (`).
+note: "Adds exporter.datadogexporter.metricremappingdisabled featuregate which disables renaming OpenTelemetry metrics to match Datadog semantics. This feature gate is only for internal use."
+
+# Mandatory: One or more tracking issues related to the change. You can use the PR number here if no issue exists.
+issues: [35025]
+
+# Optional: A list of users who contributed to the change.  This is used to generate the list of contributors in the changelog.
+change_logs: []

exporter/datadogexporter/factory.go

@@ -53,6 +53,13 @@ var metricExportNativeClientFeatureGate = featuregate.GlobalRegistry().MustRegis
 	featuregate.WithRegisterDescription("When enabled, metric export in datadogexporter uses native Datadog client APIs instead of Zorkian APIs."),
 )
 
+var metricRemappingDisableddFeatureGate = featuregate.GlobalRegistry().MustRegister(
+	"exporter.datadogexporter.metricremappingdisabled",
+	featuregate.StageAlpha,
+	featuregate.WithRegisterDescription("When enabled the Datadog Exporter remaps OpenTelemetry semantic conventions to Datadog semantic conventions. This feature gate is only for internal use."),
+	featuregate.WithRegisterReferenceURL("https://docs.datadoghq.com/opentelemetry/schema_semantics/metrics_mapping/"),
+)
+
 // noAPMStatsFeatureGate causes the trace consumer to skip APM stats computation.
 var noAPMStatsFeatureGate = featuregate.GlobalRegistry().MustRegister(
 	"exporter.datadogexporter.DisableAPMStats",
@@ -65,6 +72,11 @@ func isMetricExportV2Enabled() bool {
 	return metricExportNativeClientFeatureGate.IsEnabled()
 }
 
+// isMetricRemappingDisabled returns true if the datadogexporter should generate Datadog-compliant metrics from OpenTelemetry metrics
+func isMetricRemappingDisabled() bool {
+	return metricRemappingDisableddFeatureGate.IsEnabled()
+}
+
 func isLogsAgentExporterEnabled() bool {
 	return logsAgentExporterFeatureGate.IsEnabled()
 }

exporter/datadogexporter/metrics_exporter.go

@@ -55,7 +55,12 @@ func translatorFromConfig(set component.TelemetrySettings, cfg *Config, attrsTra
 	options := []otlpmetrics.TranslatorOption{
 		otlpmetrics.WithDeltaTTL(cfg.Metrics.DeltaTTL),
 		otlpmetrics.WithFallbackSourceProvider(sourceProvider),
-		otlpmetrics.WithRemapping(),
+	}
+
+	if isMetricRemappingDisabled() {
+		set.Logger.Warn("Metric remapping is disabled in the Datadog exporter. OpenTelemetry metrics must be mapped to Datadog semantics before metrics are exported to Datadog (ex: via a processor).")
+	} else {
+		options = append(options, otlpmetrics.WithRemapping())
 	}
 
 	if cfg.Metrics.HistConfig.SendAggregations {