perf: optimize WebSocket listener removal to avoid repeated Arrays.asList

[PerrierBouteille]

Problem:

this.webSocketListeners.removeIf(listener -> Arrays.asList(listeners).contains(listener));

creates an Arrays.asList(listeners) allocation to each iteration of removeIf, with a linear contains test on this temporary list.

Fix

Set<WebSocketListener> toRemove = Set.of(listeners);
this.webSocketListeners.removeIf(toRemove::contains);

Materialize once all the listeners to be removed and use a search by Set.