Prometheus: Update FrameType and make __name__ the field name (#62694)

These changes would make the response more in line with the dataplane contract, changes are under the feature toggle prometheusDataplane

pkg/services/featuremgmt/registry.go

@@ -454,5 +454,11 @@ var (
 			State:       FeatureStateBeta,
 			Owner:       grafanaObservabilityLogsSquad,
 		},
+		{
+			Name:        "prometheusDataplane",
+			Description: "Changes responses to from Prometheus to be compliant with the dataplane specification. In particular it sets the numeric Field.Name from 'Value' to the value of the `__name__` label when present.",
+			State:       FeatureStateAlpha,
+			Owner:       grafanaObservabilityMetricsSquad,
+		},
 	}
 )

pkg/services/featuremgmt/toggles_gen.csv

@@ -67,3 +67,4 @@ timeSeriesTable,alpha,@grafana/app-o11y,false,false,false,true
 influxdbBackendMigration,alpha,@grafana/observability-metrics,false,false,false,true
 clientTokenRotation,alpha,@grafana/grafana-authnz-team,false,false,false,false
 disableElasticsearchBackendExploreQuery,beta,@grafana/observability-logs,false,false,false,false
+prometheusDataplane,alpha,@grafana/observability-metrics,false,false,false,false

pkg/services/featuremgmt/toggles_gen.go

@@ -278,4 +278,8 @@ const (
 	// FlagDisableElasticsearchBackendExploreQuery
 	// Disable executing of Elasticsearch Explore queries trough backend
 	FlagDisableElasticsearchBackendExploreQuery = "disableElasticsearchBackendExploreQuery"
+
+	// FlagPrometheusDataplane
+	// Changes responses to from Prometheus to be compliant with the dataplane specification. In particular it sets the numeric Field.Name from 'Value' to the value of the `__name__` label when present.
+	FlagPrometheusDataplane = "prometheusDataplane"
 )