[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/staticField.kt

@@ -0,0 +1,32 @@
+// DONT_TARGET_EXACT_BACKEND: JS JS_IR JS_IR_ES6 WASM NATIVE
+// MODULE: lib
+// FILE: test/E.java
+
+package test;
+
+import java.util.Set;
+import java.util.EnumSet;
+
+public enum E {
+    INSTANCE;
+    
+    public static int foo = 42;
+    
+    public static final Set<E> INSTANCES = EnumSet.of(INSTANCE);
+}
+
+// MODULE: main(lib)
+// FILE: 1.kt
+
+import test.E
+
+fun box(): String {
+    val instances = E.INSTANCES
+    if (E.foo != 42)
+        return "Wrong foo ${E.foo}"
+    if (instances.size != 1)
+        return "Wrong size ${instances.size}"
+    if (E.INSTANCES.iterator().next() != E.INSTANCE)
+        return "Wrong instance ${E.INSTANCES.iterator().next()}"
+    return "OK"
+}