fix: Prepares for IPooledEnumerable removal (#1548)

### Summary

- Removes `IPooledEnumerable` (non-generic)
- Changes `IPooledEnumerable<T>` so that  `Free()` is replaced with the `IDisposable` pattern

Projects/UOContent/Skills/Tracking/Tracking.cs

@@ -225,7 +225,6 @@ namespace Server.SkillHandlers
                     list.Add(m);
                 }
             }
-            eable.Free();
 
             if (list.Count > 0)
             {