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/UOContent/Gumps/Props/PropsGump.cs

@@ -303,7 +303,7 @@ namespace Server.Gumps
 
                         var type = prop.PropertyType;
 
-                        if (IsType(type, OfMobile) || IsType(type, OfItem))
+                        if (IsType(type, OfEntity))
                         {
                             from.SendGump(new SetObjectGump(prop, from, m_Object, type, this));
                         }