Core/Unit: Remove a superfluous threat state update in SetPhaseMask.

Port From (https://github.com/TrinityCore/TrinityCore/commit/14bda72751a1164af055ec04e4f4c928df4c3e65)

Source/Game/Entities/Unit/Unit.cs

@@ -1182,11 +1182,7 @@ namespace Game.Entities
 
         public void OnPhaseChange()
         {
-            if (!IsInWorld)
-                return;
 
-            if (IsTypeId(TypeId.Unit) || !ToPlayer().GetSession().PlayerLogout())
-                m_threatManager.UpdateOnlineStates(true, true);
         }
 
         public uint GetModelForForm(ShapeShiftForm form, uint spellId)