Merge boxWithStdlib testData into box, delete BoxWithStdlib test

compiler/testData/codegen/box/synchronized/value.kt

@@ -0,0 +1,12 @@
+// WITH_RUNTIME
+
+fun box(): String {
+    var obj = "0" as java.lang.Object
+    val result = synchronized (obj) {
+        239
+    }
+
+    if (result != 239) return "Fail: $result"
+
+    return "OK"
+}