Preserve Mockito's subclass behavior

With Mockito 5, the library has switched to using
inline mocks by default.
We almost certainly can support this, but it needs
more investigation.
For the time being it makes sense to preserve the
mocking behavior users are used to since Quarkus 1.x

Closes: #31251

test-framework/junit5-mockito/pom.xml

@@ -31,7 +31,7 @@
         </dependency>
         <dependency>
             <groupId>org.mockito</groupId>
-            <artifactId>mockito-core</artifactId>
+            <artifactId>mockito-subclass</artifactId>
         </dependency>
         <dependency>
             <groupId>io.quarkus</groupId>