Prometheus: Implement Streaming JSON Parser (#48477)

use `prometheusStreamingJSONParser` feature toggle to enable

pkg/services/featuremgmt/registry.go

@@ -254,5 +254,10 @@ var (
 			State:        FeatureStateAlpha,
 			FrontendOnly: true,
 		},
+		{
+			Name:        "prometheusStreamingJSONParser",
+			Description: "Enable streaming JSON parser for Prometheus datasource",
+			State:       FeatureStateAlpha,
+		},
 	}
 )