FEAT(otel): enable Target Allocator for metrics

- Enable Target Allocator with consistent-hashing strategy
- Configure prometheus receiver to use Target Allocator
- Add RBAC permissions for secrets and events
- Use prometheusCR for ServiceMonitor/PodMonitor discovery

opentelemetry-collector/manifests/rbac.yaml

@@ -59,6 +59,14 @@ rules:
   - apiGroups: [""]
     resources: ["pods", "nodes", "services", "endpoints", "namespaces"]
     verbs: ["get", "watch", "list"]
+  # Secrets for TLS certificates referenced by ServiceMonitors
+  - apiGroups: [""]
+    resources: ["secrets", "configmaps"]
+    verbs: ["get", "watch", "list"]
+  # Events for status reporting
+  - apiGroups: [""]
+    resources: ["events"]
+    verbs: ["create", "patch"]
   - apiGroups: ["discovery.k8s.io"]
     resources: ["endpointslices"]
     verbs: ["get", "watch", "list"]