Spring Drop JettyHttpHandlerAdapter in favor of JettyCoreHttpHandlerAdapter / ServletHttpHandlerAdapter

Our new JettyCoreHttpHandlerAdapter for Jetty 12 supersedes the Servlet bridge for Jetty in general. That aside, as of Servlet 6.1, there is ByteBuffer support in ServletInputStream/ServletOutputStream out of the box; a Jetty-specific subclass of ServletHttpHandlerAdapter won't be necessary for that purpose anymore.

Comment From: bclozel

Done in 3b65506c13f18535e2fb055fd790bf45e