REVERT(otel): remove metrics collection, keep logs/traces only

- Revert to simpler architecture where Prometheus scrapes metrics directly via ServiceMonitors
- OTel Collector only handles logs (filelog) and traces (otlp)
- Remove Target Allocator and metrics-related config
- This reduces complexity and resource usage for home cluster

opentelemetry-collector/manifests/rbac.yaml

@@ -59,14 +59,6 @@ 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"]