Attempt to reset Servlet response in DispatcherServlet

This is a follow-up change related to gh-31104.
This change reverts the changes previously made in
`ExceptionHandlerExceptionResolver` and instead attempts to reset the
response directly in `DispatcherServlet` in order to cover all types or
exception handling.

Unlike the previous change, we decided to continue even if the response
was already committed: exception handlers will have a chance to be
called, even if it means they'll have to operate on a garbled response.
This change will cause less disruption, in case existing exception
handlers were relying on this behavior.

See gh-31104

spring-webmvc/src/main/java/org/springframework/web/servlet/DispatcherServlet.java

@@ -1338,6 +1338,13 @@ public class DispatcherServlet extends FrameworkServlet {
 
 		// Success and error responses may use different content types
 		request.removeAttribute(HandlerMapping.PRODUCIBLE_MEDIA_TYPES_ATTRIBUTE);
+		// Reset the response if the response is not committed already
+		try {
+			response.reset();
+		}
+		catch (IllegalStateException illegalStateException) {
+			// the response is already committed, leave it to exception handlers anyway
+		}
 
 		// Check registered HandlerExceptionResolvers...
 		ModelAndView exMv = null;

spring-webmvc/src/main/java/org/springframework/web/servlet/mvc/method/annotation/ExceptionHandlerExceptionResolver.java

@@ -401,9 +401,9 @@ public class ExceptionHandlerExceptionResolver extends AbstractHandlerMethodExce
 
 		ServletWebRequest webRequest = new ServletWebRequest(request, response);
 		ModelAndViewContainer mavContainer = new ModelAndViewContainer();
+
 		ArrayList<Throwable> exceptions = new ArrayList<>();
 		try {
-			response.reset();
 			if (logger.isDebugEnabled()) {
 				logger.debug("Using @ExceptionHandler " + exceptionHandlerMethod);
 			}