ISTIO service mesh between Trino nodes causes shutdown hang

When Trino workers and coordinator communicate through ISTIO service mesh proxy, workers hang during shutdown when ISTIO returns HTTP 503 errors. The proxy responses hold connections and prevent proper shutdown. This is especially problematic with asymmetric communication (workers to coordinator via ISTIO, coordinator to workers directly).

Avoid placing service mesh proxies between Trino nodes as this deployment pattern is explicitly discouraged. If ISTIO must be used, configure separate ports for internal Trino communication (e.g., port 8061 for worker-to-coordinator) versus client-facing API (port 8060), keeping internal communication outside ISTIO's control plane.