RichTextBlock with inline hyperlink fails Accessibility Insights Tool test when hyperlink isn't visible

### Describe the bug

I have a RichTextBlock with hyperlink inside a ScrollViewer. The IsOffscreen property of that hyperlink isn't updated properly when the hyperlink is out of view.
It makes Accessibility Insights Tool fail with "An on-screen element must not have a null BoundingRectangle property."

### Why is this important?

This issue may cause a confusion for users depending on this accessibility feature when there's a hyperlink in the RichTextBlock content

### Steps to reproduce the bug

[TextBlockHyperlinkIssue.zip](https://github.com/user-attachments/files/24909085/TextBlockHyperlinkIssue.zip)

1a. Make a new project using WinUI template and add following structure, for example in MainWindow.xaml:
```

Text long enough to hide the hyperlink below ...
some link

```
1b. Use attached example project
2. Start the app
3. Make sure the hyperlink isn't visible in the app window
4. Start Accessibility Insights Tool
5. Run automated checks on the app

### Actual behavior

Automated check finds a failure on the hyperlink: "An on-screen element must not have a null BoundingRectangle property."

### Expected behavior

Accessibility test shouldn't fail

### Screenshots

Failing, hyperlink not visible:

Passing, hyperlink visible:

### NuGet package version

WinUI 3 - Windows App SDK 1.8.3: 1.8.251106002

### Windows version

Windows 11 (24H2): Build 26100

### Additional context

_No response_

Start with the attached reproduction project and the RichTextBlock, ScrollViewer, and Hyperlink structure described in the issue. Compare the hyperlink's automation properties when it is visible versus scrolled out of view, then run Accessibility Insights automated checks; done means the hidden hyperlink no longer triggers the null BoundingRectangle failure.

Written by the indexing model from the issue text.