Remove unused using System after IDisposable removal

Co-authored-by: andyleejordan <2226434+andyleejordan@users.noreply.github.com>

Author: Copilot

src/PowerShellEditorServices/Hosting/EditorServicesServerFactory.cs

@@ -1,7 +1,6 @@
 // Copyright (c) Microsoft Corporation.
 // Licensed under the MIT License.
 
-using System;
 using System.IO;
 using Microsoft.Extensions.DependencyInjection;
 using Microsoft.Extensions.Logging;