Merge boxWithStdlib testData into box, delete BoxWithStdlib test

compiler/testData/codegen/box/reflection/enclosing/kt6368.kt

@@ -0,0 +1,25 @@
+// WITH_REFLECT
+
+import java.util.HashMap
+
+interface R {
+    fun result(): String
+}
+
+val a by lazy {
+    with(HashMap<String, R>()) {
+        put("result", object : R {
+            override fun result(): String = "OK"
+        })
+        this
+    }
+}
+
+fun box(): String {
+    val r = a["result"]!!
+
+    // Check that reflection won't fail
+    r.javaClass.getEnclosingMethod().toString()
+
+    return r.result()
+}