lb-ip-binder: use KUBERNETES_SERVICE_{HOST,PORT} env vars

hostNetwork pods don't go through CoreDNS by default, so the
kubernetes.default.svc hostname doesn't resolve and the reconcile
loop silently failed on the curl. The auto-injected
KUBERNETES_SERVICE_HOST/PORT env vars give the apiserver Service
IP+port directly — Cilium kpr DNATs the ClusterIP to a live
apiserver endpoint.

kubernetes/infrastructure/lb-ip-binder/daemonset.yaml

@@ -58,7 +58,11 @@ data:
     set -u
     TOKEN=$(cat /var/run/secrets/kubernetes.io/serviceaccount/token)
     CA=/var/run/secrets/kubernetes.io/serviceaccount/ca.crt
-    API=https://kubernetes.default.svc
+    # hostNetwork pods don't use CoreDNS by default, so the
+    # kubernetes.default.svc hostname doesn't resolve. Use the
+    # auto-injected env vars instead — they hold the apiserver Service
+    # IP+port that Cilium's kpr DNATs to a real apiserver endpoint.
+    API="https://${KUBERNETES_SERVICE_HOST}:${KUBERNETES_SERVICE_PORT}"
 
     # Ensure dummy0 exists and is up. Cilium creates it on startup but
     # we don't depend on that.