metropolis/node/core/metrics: migrate labels to sd-meta naming scheme

Change-Id: Ie5ad32d5383abbe13ff9c347d47ecc10f090bccb
Reviewed-on: https://review.monogon.dev/c/monogon/+/1971
Reviewed-by: Leopold Schabel <leo@monogon.tech>
Tested-by: Jenkins CI
diff --git a/metropolis/node/core/metrics/metrics.go b/metropolis/node/core/metrics/metrics.go
index 05377b5..7126459 100644
--- a/metropolis/node/core/metrics/metrics.go
+++ b/metropolis/node/core/metrics/metrics.go
@@ -252,9 +252,9 @@
 			s.sdResp = append(s.sdResp, sdTarget{
 				Targets: []string{n.Status.ExternalAddress},
 				Labels: map[string]string{
-					"kubernetes_worker":     fmt.Sprintf("%t", n.Roles.KubernetesWorker != nil),
-					"consensus_member":      fmt.Sprintf("%t", n.Roles.ConsensusMember != nil),
-					"kubernetes_controller": fmt.Sprintf("%t", n.Roles.KubernetesController != nil),
+					"__meta_metropolis_role_kubernetes_worker":     fmt.Sprintf("%t", n.Roles.KubernetesWorker != nil),
+					"__meta_metropolis_role_kubernetes_controller": fmt.Sprintf("%t", n.Roles.KubernetesController != nil),
+					"__meta_metropolis_role_consensus_member":      fmt.Sprintf("%t", n.Roles.ConsensusMember != nil),
 				},
 			})
 		}