[Test] Properly merge box against java testdata into codegen/box

Previous commit about it was 3199ce03 and it was completely wrong

compiler/testData/codegen/box/annotations/kClassMapping/classParameterOnJavaClass.kt

@@ -0,0 +1,29 @@
+// IGNORE_BACKEND_FIR: JVM_IR
+// DONT_TARGET_EXACT_BACKEND: JS JS_IR JS_IR_ES6 WASM NATIVE
+// WITH_RUNTIME
+// MODULE: lib
+// FILE: JavaAnn.java
+
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+
+@Retention(RetentionPolicy.RUNTIME)
+@interface JavaAnn {
+    Class<?> value();
+}
+
+// FILE: MyJavaClass.java
+
+class OK {}
+
+@JavaAnn(OK.class)
+class MyJavaClass {}
+
+// MODULE: main(lib)
+// FILE: 1.kt
+
+fun box(): String {
+    val ann = MyJavaClass::class.java.getAnnotation(JavaAnn::class.java)
+    if (ann == null) return "fail: cannot find JavaAnn on MyClass"
+    return ann.value.java.simpleName!!
+}