[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/enum/simpleJavaEnumWithFunction.kt

@@ -0,0 +1,31 @@
+// DONT_TARGET_EXACT_BACKEND: JS JS_IR JS_IR_ES6 WASM NATIVE
+// MODULE: lib
+// FILE: test/En.java
+
+package test;
+
+import java.lang.Override;
+import java.lang.String;
+
+public enum En {
+    A {
+        @Override
+        public String repr() {
+            return "A";
+        }
+    },
+    B;
+    
+    public String repr() {
+        return "ololol" + toString();
+    }
+}
+
+// MODULE: main(lib)
+// FILE: 1.kt
+
+import test.En.*
+
+fun box() =
+    if (A.repr() == "A" && B.repr() == "olololB") "OK"
+    else "fail"