PERF(observability): reduce replicas, add priority

- Reduce Prometheus replicas from 2 to 1
- Reduce Grafana replicas from 2 to 1
- Reduce Blackbox-exporter replicas from 2 to 1
- Move Loki, Thanos, Tempo to workers (remove tolerations)
- Add medium-priority to Prometheus, Loki, Thanos, Tempo

tempo/helm-values.yaml

@@ -7,13 +7,8 @@
 # - OTLP receiver for OpenTelemetry data
 # - Integrates with Grafana for trace visualization
 
-# Run on master node for stability
-tolerations:
-  - key: node-role.kubernetes.io/control-plane
-    operator: Exists
-    effect: NoSchedule
-nodeSelector:
-  node-role.kubernetes.io/control-plane: "true"
+# Medium priority for observability
+priorityClassName: medium-priority
 
 # =============================================================================
 # Resource Limits (optimized for small cluster)