[Bug][Grid] Grouping does not retain collapsed/expanded items

[filipKovachev]

Describe the bug
When using virtualization with grouping, the expand/collapsed items are not retained

To Reproduce
Steps to reproduce the behavior:

1. Open this example: https://stackblitz.com/edit/521xejuk?file=src%2Fmain.vue
2. Collapse the first item Condiments.
3. Scroll to down a bit and then to the top so that Condiments is visible
4. Notice that the previously collapsed item is now expanded

Second related issue (page event doesn't get fired on when collapsing to many rows):

1. Open the preview in a seperate tab else it just doesn't render the way it should.
2. Don't scroll, just collapse the groups one by one from the top down:

Expected behavior
When collapse/expnading an item, scrolling down and then back the state should persist and the next rows should be added to the view port.

Browser

• OS: [for example, iOS]
• Browser [for example, Chrome, Safari]
• Version [for example, 22]

More information in Ticket 1685421