Delete generated test cases, move testData to boxWithStdlib

compiler/testData/codegen/boxWithStdlib/dataClasses/twoVarParams.kt

@@ -0,0 +1,9 @@
+data class A(var x: Int, var y: String)
+
+fun box(): String {
+    val a = A(21, "K")
+    if (a.component1() != 21 || a.component2() != "K") return "Fail"
+    a.x *= 2
+    a.y = "O" + a.component2()
+    return if (a.component1() == 42) a.component2() else a.component1().toString()
+}