Fix FreeMarker tests for JDK21 build

Prior to this commit, some FreeMarker tests would fail when involving
property lookup in a template file, where this bean property is linked
with a method implemented as a default method on an interface.

While I did not manage to reproduce this behavior in an independent test
case, this is most likely related to a change in JDK 21:
https://bugs.openjdk.org/browse/JDK-8071693

This commit changes the template expression to using the default method
directly.

spring-webflux/src/test/resources/org/springframework/web/reactive/result/view/freemarker/test-macro.ftl

@@ -7,7 +7,7 @@ NAME
 ${command.name}
 
 AGE
-${command.age}
+${command.age()}
 
 MESSAGE
 <@spring.message "hello"/> <@spring.message "world"/>

spring-webmvc/src/test/resources/org/springframework/web/servlet/view/freemarker/test.ftl

@@ -7,7 +7,7 @@ NAME
 ${command.name}
 
 AGE
-${command.age}
+${command.age()}
 
 MESSAGE
 <@spring.message "hello"/> <@spring.message "world"/>