Update KeepAliveHandler.java (Azure#43968)

Send the ping contents when responding to pong.

Author: jjoslin

sdk/openai/azure-ai-openai-realtime/src/main/java/com/azure/ai/openai/realtime/implementation/websocket/KeepAliveHandler.java

@@ -37,7 +37,7 @@ public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception
             // Ping, reply Pong
             LOGGER.atVerbose().log(() -> "Received PingWebSocketFrame");
             LOGGER.atVerbose().log(() -> "Sending PongWebSocketFrame");
-            ch.writeAndFlush(new PongWebSocketFrame());
+            ch.writeAndFlush(new PongWebSocketFrame(frame.copy().content()));
         } else if (frame instanceof PongWebSocketFrame) {
             // Pong
             LOGGER.atVerbose().log(() -> "Received PongWebSocketFrame");