Rendering issue with rounded corners

[kmelmon]

Describe the bug

When using certain sizes in combination with rounded corners, there's a rendering bug - the child of the element with rounded corners can have its corners "poke out" instead of being clipped to the rounded corner.

Steps to reproduce the bug

Steps to reproduce the behavior:
Create an app with this markup:

    <Canvas>
        <Grid BorderBrush="Black" BorderThickness="3" CornerRadius="10">
            <StackPanel
          Orientation="Horizontal"
          Background="Red"
          BorderThickness="0"
          BorderBrush="Green">
                <TextBlock Text="Hello World XAML!" />
                <TextBlock Text="TextBlock #2" VerticalAlignment="Center" />
            </StackPanel>
        </Grid>
    </Canvas>


```**Expected behavior**
<!-- Please provide a description of what you expected to happen-->
The red background should be clipped inside the rounded corners

**Version Info**
This is with inbox XAML on rs_onecore_dep 190706.  Issue likely repro's on builds back to RS2 or so, when we first added rounded corner clipping via dcomp.

<!-- Which device form factors did you see the issue on? Leave blank if you didn't try that device. -->
Desktop

[JJBrychell]

I am unable to repro this issue in any WINUI 3 releases since 1.1 or in System Xaml, so am going to close it as fixed (since obviously at some point it existed given the image included above).