Merge boxWithStdlib testData into box, delete BoxWithStdlib test

compiler/testData/codegen/box/jvmStatic/syntheticAccessor.kt

@@ -0,0 +1,17 @@
+// WITH_RUNTIME
+
+class C {
+    companion object {
+        private @JvmStatic fun foo(): String {
+            return "OK"
+        }
+    }
+
+    fun bar(): String {
+        return foo()
+    }
+}
+
+fun box(): String {
+    return C().bar()
+}