[GameState] Optimize IsDiskPartitionExist method

about 50% faster on checking Hi3 Cache (1.2ms -> 550ms) by not copying and casting the results twice

Author: bagusnl

CollapseLauncher/Classes/GameManagement/Versioning/GameVersionBase.GameState.cs

@@ -263,15 +263,9 @@ protected virtual bool IsDiskPartitionExist(string? path)
         {
             try
             {
-                ReadOnlySpan<char> pathRoot = Path.GetPathRoot(path);
-                if (pathRoot.IsEmpty)
-                {
-                    return false;
-                }
-
-                string pathRootStr = pathRoot.ToString();
-                // Return from Directory.Exists() since the IsReady property use the same method.
-                return Directory.Exists(pathRootStr);
+                var pathRoot = Path.GetPathRoot(path);
+                return !string.IsNullOrEmpty(pathRoot) && Directory.Exists(pathRoot);
+                       // Return from Directory.Exists() since the IsReady property use the same method.
             }
             catch (Exception)
             {