Enable JsonNewtonsoftPocoChangeTrackingTest with MariaDB skip

Changed from internal to public and added [SupportedServerVersionLessThanCondition(nameof(ServerVersionSupport.JsonDataTypeEmulation))] to skip tests on MariaDB.

Tested on both databases:
- MySQL 8.0.40: All 14 tests passing
- MariaDB 10.5.27: All tests properly skipped (JsonDataTypeEmulation active)

This test suite validates JSON change tracking functionality using Newtonsoft.Json serialization.

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

Author: Copilot

test/EFCore.MySql.FunctionalTests/Query/JsonNewtonsoftPocoChangeTrackingTest.cs

@@ -9,9 +9,10 @@
 
 namespace Pomelo.EntityFrameworkCore.MySql.FunctionalTests.Query
 {
-    // Disabled via internal access. JSON functionality is not currently supported.
+    // Re-enabled to test JSON change tracking functionality with Newtonsoft.Json
     [SupportedServerVersionCondition(nameof(ServerVersionSupport.Json))]
-    internal class JsonNewtonsoftPocoChangeTrackingTest : JsonPocoChangeTrackingTestBase<JsonNewtonsoftPocoChangeTrackingTest.JsonNewtonsoftPocoChangeTrackingFixture>
+    [SupportedServerVersionLessThanCondition(nameof(ServerVersionSupport.JsonDataTypeEmulation))]
+    public class JsonNewtonsoftPocoChangeTrackingTest : JsonPocoChangeTrackingTestBase<JsonNewtonsoftPocoChangeTrackingTest.JsonNewtonsoftPocoChangeTrackingFixture>
     {
         public JsonNewtonsoftPocoChangeTrackingTest(JsonNewtonsoftPocoChangeTrackingFixture fixture, ITestOutputHelper testOutputHelper)
             : base(fixture)