Menu append method replaces the parent item instead of appending the new item as child

[martintabakov]

Bug report

When you try to append a child item in the Menu, the parent item is replaced instead.

Regression introduced with 2022 R1

Reproduction of the problem

1. Open this Dojo example.
2. Click the Append 2 button
3. Check Item 2

Current behavior

The new item replaces Sub Item 1

Expected/desired behavior

The new item should be appended as a child to Sub Item 1

Environment

• Kendo UI version: 2022.2.802
• Browser: [all]