Adjusts setRequestHandler javadoc in CsrfWebFilter

Adjusts setRequestHandler method javadoc in CsrfWebFilter class to reflect changes in 6.0.

In 6.0, the default ServerCsrfTokenRequestHandler changed to XorServerCsrfTokenRequestAttributeHandler, however, the javadoc for the setRequestHandler method still said it was ServerCsrfTokenRequestAttributeHandler.

This change adjusts the information to make it more accurate, because, although XorServerCsrfTokenRequestAttributeHandler is a subclass of ServerCsrfTokenRequestAttributeHandler, the behavior is quite different.

Closes gh-12465

web/src/main/java/org/springframework/security/web/server/csrf/CsrfWebFilter.java

@@ -104,7 +104,7 @@ public class CsrfWebFilter implements WebFilter {
 	 * Specifies a {@link ServerCsrfTokenRequestHandler} that is used to make the
 	 * {@code CsrfToken} available as an exchange attribute.
 	 * <p>
-	 * The default is {@link ServerCsrfTokenRequestAttributeHandler}.
+	 * The default is {@link XorServerCsrfTokenRequestAttributeHandler}.
 	 * @param requestHandler the {@link ServerCsrfTokenRequestHandler} to use
 	 * @since 5.8
 	 */