[iOS] KeepItemsInView Does Not Show Newly Added Items After Scrolling Down in CollectionView

### Description

The KeepItemsInView mode in CollectionView does not work as expected after scrolled down. The newly added item does not appear in the view after scrolling down.

https://github.com/user-attachments/assets/b86563c3-7693-4063-bc1a-b17f7b41f6a3

### Steps to Reproduce

1. Run the attached file [ItemsUpdatingScrollModeIssue 2.zip](https://github.com/user-attachments/files/19866804/ItemsUpdatingScrollModeIssue.2.zip)
2. Select KeepItemsInView and tap the Add button. Observe that the newly added item appears in the view. However, after scrolling down and adding more items, notice that the newly added item does not appear in the view.

Expected Behavior:

- The newly added item should automatically appear in the view without requiring manual scrolling back to the top.

Actual Behavior:

- The newly added item does not appear in the view after scrolling down. Manual scrolling to the top is required to see the newly added item.

### Link to public reproduction project repository

_No response_

### Version with bug

9.0.60 SR6

### Is this a regression from previous behavior?

Not sure, did not test other versions

### Last version that worked well

_No response_

### Affected platforms

iOS, macOS

### Affected platform versions

_No response_

### Did you find any workaround?

_No response_

### Relevant log output

```shell

```

Start by running the attached ItemsUpdatingScrollModeIssue 2.zip reproduction on iOS or macOS and exercising CollectionView with KeepItemsInView after scrolling and adding items. Trace the update and scrolling behavior, then verify that each newly added item automatically appears in view without manually returning to the top.

Written by the indexing model from the issue text.