apply 4,4,0,0 cornerradius to filled AutoSuggestBox style (#3793)

Author: corvinsz

src/MaterialDesignThemes.Wpf/Themes/MaterialDesignTheme.AutoSuggestBox.xaml

@@ -612,7 +612,7 @@
     <Setter Property="Background" Value="{DynamicResource MaterialDesign.Brush.TextBox.FilledBackground}" />
     <Setter Property="Padding" Value="{x:Static wpf:Constants.FilledTextBoxDefaultPadding}" />
     <Setter Property="wpf:TextFieldAssist.HasFilledTextField" Value="True" />
-    <Setter Property="wpf:TextFieldAssist.TextFieldCornerRadius" Value="4" />
+    <Setter Property="wpf:TextFieldAssist.TextFieldCornerRadius" Value="4,4,0,0" />
     <Setter Property="wpf:TextFieldAssist.UnderlineCornerRadius" Value="0" />
   </Style>