web: add slo group to request meta (#74765)

Signed-off-by: bergquist <carl.bergquist@gmail.com>

pkg/middleware/request_metrics.go

@@ -45,6 +45,10 @@ func RequestMetrics(features featuremgmt.FeatureToggles, cfg *setting.Cfg, promR
 		histogramLabels = append(histogramLabels, "team")
 	}
 
+	if features.IsEnabled(featuremgmt.FlagHttpSLOLevels) {
+		histogramLabels = append(histogramLabels, "slo_group")
+	}
+
 	httpRequestDurationHistogram := prometheus.NewHistogramVec(
 		prometheus.HistogramOpts{
 			Namespace: "grafana",
@@ -95,6 +99,10 @@ func RequestMetrics(features featuremgmt.FeatureToggles, cfg *setting.Cfg, promR
 				labelValues = append(labelValues, rmd.Team)
 			}
 
+			if features.IsEnabled(featuremgmt.FlagHttpSLOLevels) {
+				labelValues = append(labelValues, string(rmd.SLOGroup))
+			}
+
 			// avoiding the sanitize functions for in the new instrumentation
 			// since they dont make much sense. We should remove them later.
 			histogram := httpRequestDurationHistogram.