Fix globalization test on mobile platforms (#115248)

* Fix globalization test on mobile platforms

* Update src/libraries/System.Runtime/tests/System.Globalization.Tests/CultureInfo/CultureInfoCtor.cs

Co-authored-by: Copilot <[email protected]>

* minor update

* fix comment

---------

Co-authored-by: Copilot <[email protected]>

Author: tarekgh

src/libraries/System.Runtime/tests/System.Globalization.Tests/CultureInfo/CultureInfoCtor.cs

@@ -388,11 +388,28 @@ public static IEnumerable<object[]> Ctor_String_TestData()
             }
         }
 
+        public static IEnumerable<object[]> Ctor_Undetermined_TestData()
+        {
+            yield return new object[] { "und-us", "und-US", "und-US" };
+            yield return new object[] { "und-us_tradnl", "und-US", "und-US_tradnl"};
+
+            // On AppleMobile, the behavior of CultureInfo differs due to platform-specific
+            // handling of Unicode extensions and subtags. These platforms preserve the full language tag, including
+            // extensions, while other platforms normalize the tag to a simpler form.
+            if (PlatformDetection.IsAppleMobile)
+            {
+                yield return new object[] { "und-es-u-co-phoneb", "und-ES-u-co-phoneb", "und-ES-u-co-phoneb" };
+                yield return new object[] { "und-es-t-something", "und-ES-t-something", "und-ES-t-something" };
+            }
+            else
+            {
+                yield return new object[] { "und-es-u-co-phoneb", "und-ES", "und-ES_phoneb" };
+                yield return new object[] { "und-es-t-something", "und-ES", "und-ES"};
+            }
+        }
+
         [ConditionalTheory(typeof(PlatformDetection), nameof(PlatformDetection.IsIcuGlobalization))]
-        [InlineData("und-us", "und-US", "und-US")]
-        [InlineData("und-us_tradnl", "und-US", "und-US_tradnl")]
-        [InlineData("und-es-u-co-phoneb", "und-ES", "und-ES_phoneb")]
-        [InlineData("und-es-t-something", "und-ES", "und-ES")]
+        [MemberData(nameof(Ctor_Undetermined_TestData))]
         public void CtorUndeterminedLanguageTag(string cultureName, string expectedCultureName, string expectedSortName)
         {
             CultureInfo culture = new CultureInfo(cultureName);