Update tests per new default

tests/Avalonia.Controls.UnitTests/ScrollViewerTests.cs

@@ -37,7 +37,7 @@ namespace Avalonia.Controls.UnitTests
             target.HorizontalScrollBarVisibility = ScrollBarVisibility.Disabled;
             target.HorizontalScrollBarVisibility = ScrollBarVisibility.Auto;
 
-            Assert.Equal(new[] { true, false, true }, values);
+            Assert.Equal(new[] { false, true }, values);
         }
 
         [Fact]

tests/Avalonia.Layout.UnitTests/LayoutableTests_EffectiveViewportChanged.cs

@@ -162,7 +162,7 @@ namespace Avalonia.Layout.UnitTests
             {
                 var root = CreateRoot();
                 var target = new Canvas { Width = 200, Height = 200 };
-                var scroller = new ScrollViewer { Width = 100, Height = 100, Content = target, Template = ScrollViewerTemplate() };
+                var scroller = new ScrollViewer { Width = 100, Height = 100, Content = target, Template = ScrollViewerTemplate(), HorizontalScrollBarVisibility = ScrollBarVisibility.Hidden };
                 var raised = 0;
 
                 target.EffectiveViewportChanged += (s, e) =>
@@ -185,7 +185,7 @@ namespace Avalonia.Layout.UnitTests
             {
                 var root = CreateRoot();
                 var target = new Canvas { Width = 200, Height = 200 };
-                var scroller = new ScrollViewer { Width = 100, Height = 100, Content = target, Template = ScrollViewerTemplate() };
+                var scroller = new ScrollViewer { Width = 100, Height = 100, Content = target, Template = ScrollViewerTemplate(), HorizontalScrollBarVisibility = ScrollBarVisibility.Hidden };
                 var raised = 0;
 
                 root.Child = scroller;