Move some tests from boxWithStdlib/ to box/

Move those tests which do not require neither stdlib nor reflect

compiler/testData/codegen/box/regressions/kt2509.kt

@@ -0,0 +1,12 @@
+fun box(): String {
+        A()
+        return "OK"
+}
+
+class A: B() {
+        override var foo = arrayOf<Int?>(12, 13)
+}
+
+abstract class B {
+        abstract var foo: Array<Int?>
+}