Improve cancellation of read/write inactivity

The cancellation of read and write inactivity tasks was done via
WebSocketHandler#afterConnectionClosed, relying on the WebSocket
library to always invoke the callback.

This change moves the cancellation to the `close` method instead
that in turn is called from DefaultStompSession#resetConnection,
in effect making the cancellation more proactive and aligned with
connection cleanup in DefaultStompSession vs relying on a
subsequent call from the WebSocket library after the connection
is closed.

Closes gh-32195

spring-websocket/src/test/java/org/springframework/web/socket/messaging/WebSocketStompClientTests.java

@@ -302,7 +302,9 @@ class WebSocketStompClientTests {
 		tcpConnection.onReadInactivity(mock(), 2L);
 		tcpConnection.onWriteInactivity(mock(), 2L);
 
-		this.webSocketHandlerCaptor.getValue().afterConnectionClosed(this.webSocketSession, CloseStatus.NORMAL);
+		WebSocketHandler handler = this.webSocketHandlerCaptor.getValue();
+		TcpConnection<?> connection = (TcpConnection<?>) WebSocketHandlerDecorator.unwrap(handler);
+		connection.close();
 
 		verify(future, times(2)).cancel(true);
 		verifyNoMoreInteractions(future);