Wrap disconnected client exceptions as AsyncRequestNotUsableException in Servlet container onError callback

[rstoyanchev]

We raise this in StandardServletAsyncWebRequest when wrapped response I/O methods catch an IOException. However, the Servlet container may be first in reporting the same via AsyncListener#onError in which case @ExceptionHandler methods see the raw IOException making it more difficult to differentiate from any other I/O error.

We should also apply the AsyncRequestNotUsableException wrapper in WebAsyncManager, in onError handling for exceptions recognized with DisconnectedClientHelper.

Originally reported in #34005.