fix(csharp): update Hive2 namespace after repo restructure

Apache.Arrow.Adbc.Drivers.Apache.Hive2 -> AdbcDrivers.HiveServer2.Hive2

Co-authored-by: Isaac

Author: msrathore-db

csharp/test/E2E/CloudFetch/CloudFetchStragglerDownloaderE2ETests.cs

@@ -25,7 +25,7 @@
 using System.Text;
 using System.Threading;
 using System.Threading.Tasks;
-using Apache.Arrow.Adbc.Drivers.Apache.Hive2;
+using AdbcDrivers.HiveServer2.Hive2;
 using AdbcDrivers.Databricks;
 using AdbcDrivers.Databricks.Reader.CloudFetch;
 using AdbcDrivers.Databricks.Reader.CloudFetch.StragglerDownload;