Updated the UITest (dotnet#19159)

src/Controls/tests/UITests/Tests/Issues/Issue19159.cs

@@ -19,7 +19,7 @@ public void ContentShouldNotBeOverlaidByTopBar()
 			_ = App.WaitForElement("page1");
 
 			// The content should not be overlaid by top bar
-			App.Screenshot();
+			VerifyScreenshot();
 		}
 	}
 }