Clean up content type in ContentNegotiatingViewResolver

This commit removes the quality value of the selected media type before
setting it in the request attribute.

Closes gh-26315

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

@@ -344,6 +344,7 @@ public class ContentNegotiatingViewResolver extends WebApplicationObjectSupport
 				if (StringUtils.hasText(candidateView.getContentType())) {
 					MediaType candidateContentType = MediaType.parseMediaType(candidateView.getContentType());
 					if (mediaType.isCompatibleWith(candidateContentType)) {
+						mediaType = mediaType.removeQualityValue();
 						if (logger.isDebugEnabled()) {
 							logger.debug("Selected '" + mediaType + "' given " + requestedMediaTypes);
 						}