Remove generated codegen tests, move all testData to box/

A single test file will be generated out of box/ directory

compiler/testData/codegen/box/defaultArguments/constructor/annotation.kt

@@ -0,0 +1,11 @@
+annotation class A(val a: Int = 0)
+
+A fun test1() = 1
+A(2) fun test2() = 1
+
+fun box(): String {
+   if ((test1() + test2()) == 2) {
+      return "OK"
+   }
+   return "fail"
+}