Don't BringIntoViewOnFocusChange in Carousel. (#16339)

Carousel can't actually scroll controls into view because it's a paging control so this property doesn't make much sense. But what it does affect is other scroll viewers that are contained in it. If a control is focused within a scroll viewer within a carousel, then `BringIntoView` will be invoked by the carousel scroll viewer, even though the inner scroll viewer has `BringIntoViewOnFocusChange  = false`.

src/Avalonia.Themes.Fluent/Controls/Carousel.xaml

@@ -8,6 +8,7 @@
                       Background="{TemplateBinding Background}"
                       BorderBrush="{TemplateBinding BorderBrush}"
                       BorderThickness="{TemplateBinding BorderThickness}"
+                      BringIntoViewOnFocusChange="False"
                       HorizontalScrollBarVisibility="Hidden"
                       VerticalScrollBarVisibility="Hidden">
           <ItemsPresenter Name="PART_ItemsPresenter"

src/Avalonia.Themes.Simple/Controls/Carousel.xaml

@@ -8,6 +8,7 @@
                       Background="{TemplateBinding Background}"
                       BorderBrush="{TemplateBinding BorderBrush}"
                       BorderThickness="{TemplateBinding BorderThickness}"
+                      BringIntoViewOnFocusChange="False"
                       HorizontalScrollBarVisibility="Hidden"
                       VerticalScrollBarVisibility="Hidden">
           <ItemsPresenter Name="PART_ItemsPresenter"