fix: Fixes various mobile packets and setting serials (#1618)

### Summary
- Removes old death packet that isn't used. Doubtful this causes issues with clients that are v4+.
- Removes duplicate incoming packets. Again, probably to fix some old client issues, doubtful it affects clients v4+.
- Fixes setting serials and entities in props/commands. Note: Disabled setting `Parent` since the new sector code has issues. We shouldn't rely on it anyway!
- Reverts a recent change to healthbars that should not have been made. Oops!

Projects/Server/Items/Item.cs

@@ -585,7 +585,8 @@ public class Item : IHued, IComparable<Item>, ISpawnable, IObjectPropertyListEnt
         }
     }
 
-    [CommandProperty(AccessLevel.GameMaster, AccessLevel.Developer)]
+    // Note: Setting the parent via command/props causes problems.
+    [CommandProperty(AccessLevel.GameMaster, readOnly: true)]
     public IEntity Parent
     {
         get => m_Parent;