Revert "Use uniform-to-fill stretch for background images instead of full stretch"

This reverts commit b255bae21ad46d70d86b2f70b6d17237d9ee10e3.

Reverting because I don't want to break anyone's existing flow especially since I don't think this has been requested. Committed anyway just to have a record of it.

DesktopClock/MainWindow.xaml

@@ -120,8 +120,7 @@
                                 <Setter Property="Background">
                                     <Setter.Value>
                                         <ImageBrush Opacity="{Binding BackgroundOpacity, Source={x:Static p:Settings.Default}, Mode=OneWay}"
-                                                    ImageSource="{Binding BackgroundImagePath, Source={x:Static p:Settings.Default}, Mode=OneWay}"
-                                                    Stretch="UniformToFill" />
+                                                    ImageSource="{Binding BackgroundImagePath, Source={x:Static p:Settings.Default}, Mode=OneWay}" />
                                     </Setter.Value>
                                 </Setter>
                             </DataTrigger.Setters>