Change DisclaimerStyle to be non-italic (#16272)

This changes the appearance of the disclaimer text that is used on some
of the settings pages. The italic text style is replaced with a neutral
style that fits better with the rest of the UI.

## Detailed Description of the Pull Request / Additional comments
I also tried out these alternative styles but overall preferred the
default TextBlock style (BodyTextBlockStyle).

Closes #16264.

src/cascadia/TerminalSettingsEditor/CommonResources.xaml

@@ -115,7 +115,6 @@
     <!--  Used for disclaimers  -->
     <Style x:Key="DisclaimerStyle"
            TargetType="TextBlock">
-        <Setter Property="FontStyle" Value="Italic" />
         <Setter Property="TextWrapping" Value="WrapWholeWords" />
         <Setter Property="MaxWidth" Value="1000" />
     </Style>