This commit ensures handling is cancelled in case of onError/Timeout
callback from the Servlet container.
Separately we detect the same in ServletServerHttpRequest and
ServletServerHttpResponse, which signal onError to the read publisher
and cancel writing, but if the onError/Timeout arrives after reading
is done and before writing has started (e.g. longer handling), then
neither will reach handling.
See gh-26434, gh-26407
c2137a0d2f