Core/AreaTriggers: Handle exit areatrigger on player map change

Port From (https://github.com/TrinityCore/TrinityCore/commit/26fc14419142e3188370035ce4144cdb125bec05)

Source/Game/Entities/Unit/Unit.Fields.cs

@@ -101,6 +101,7 @@ namespace Game.Entities
         DiminishingReturn[] m_Diminishing = new DiminishingReturn[(int)DiminishingGroup.Max];
         protected List<GameObject> m_gameObj = new();
         List<AreaTrigger> m_areaTrigger = new();
+        List<AreaTrigger> m_insideAreaTriggers = new();
         protected List<DynamicObject> m_dynObj = new();
         protected float[] CreateStats = new float[(int)Stats.Max];
         float[] m_floatStatPosBuff = new float[(int)Stats.Max];