Ensure local @CrossOrigin maxAge overrides global value

Prior to this commit, a method-level @CrossOrigin maxAge value did not
override a class-level @CrossOrigin maxAge value. This contradicts the
Javadoc for @CrossOrgin which states the following.

    For those attributes where only a single value can be accepted such
    as allowCredentials and maxAge, the local overrides the global
    value.

This commit ensures that a method-level @CrossOrigin maxAge value
overrides a class-level @CrossOrigin maxAge value.

Closes gh-26619

spring-webflux/src/main/java/org/springframework/web/reactive/result/method/annotation/RequestMappingHandlerMapping.java

@@ -341,7 +341,7 @@ public class RequestMappingHandlerMapping extends RequestMappingInfoHandlerMappi
 					"or an empty string (\"\"): current value is [" + allowCredentials + "]");
 		}
 
-		if (annotation.maxAge() >= 0 && config.getMaxAge() == null) {
+		if (annotation.maxAge() >= 0) {
 			config.setMaxAge(annotation.maxAge());
 		}
 	}