[inflight/current] [Testing] Fix for flaky UITests Issue18896 and disable Issue14471 test which fails in CI randomly (#28540)

* Improve stability for flaky test

* Update Issue14471.cs

* Don t allow pre release

---------

Co-authored-by: HarishKumarSF4517 <harish.kumar@syncfusion.com>
Co-authored-by: Rui Marinho <me@ruimarinho.net>

Author: 3 people

global.json

@@ -8,6 +8,6 @@
     "Microsoft.DotNet.Arcade.Sdk": "9.0.0-beta.25161.4"
   },
   "sdk": {
-    "allowPrerelease": true
+    "allowPrerelease": false
   }
 }

src/Controls/tests/TestCases.HostApp/Issues/Issue18896.xaml.cs

@@ -1,6 +1,6 @@
 namespace Maui.Controls.Sample.Issues
 {
-	[Issue(IssueTracker.ManualTest, "C3", "Can scroll ListView inside RefreshView", PlatformAffected.All)]
+	[Issue(IssueTracker.ManualTest, "C3", "Can scroll ListView inside RefreshView", PlatformAffected.All, isInternetRequired: true)]
 	public partial class Issue18896 : ContentPage
 	{
 		public Issue18896()

src/Controls/tests/TestCases.Shared.Tests/Tests/Issues/Issue14471.cs

@@ -1,4 +1,5 @@
-using NUnit.Framework;
+#if TEST_FAILS_ON_ANDROID // This test fails randomly, likely because the image source has disappeared sometimes in CI, not able to reproduce locally. For now, we have ignored the test for Android. Issue for re-enabling: https://github.com/dotnet/maui/issues/24243
+using NUnit.Framework;
 using UITest.Appium;
 using UITest.Core;
 
@@ -23,4 +24,5 @@ public void ImageDoesntDisappearWhenNavigatingBack()
 		// The test passes if image is loaded
 		VerifyScreenshot();
 	}
-}
+}
+#endif

src/Controls/tests/TestCases.Shared.Tests/Tests/Issues/Issue18896.cs

@@ -22,6 +22,7 @@ public Issue18896(TestDevice device) : base(device)
 		[FailsOnWindowsWhenRunningOnXamarinUITest("Currently fails on Windows; see https://github.com/dotnet/maui/issues/15994")]
 		public void Issue18896Test()
 		{
+			VerifyInternetConnectivity();
 			App.WaitForElement("WaitForStubControl");
 
 			App.ScrollDown(ListView);