Core/Spells: SpellAttr8 fixups - use creator instead of owner for SPELL_ATTR8_ONLY_TARGET_IF_SAME_CREATOR and removed cast time requirement for channelled spell predicted healing

Port From (https://github.com/TrinityCore/TrinityCore/commit/930a08fe03a033a6bb30fb8c94a8490c4b77fe91)

Source/Game/Entities/AreaTrigger/AreaTrigger.cs

@@ -1467,6 +1467,7 @@ namespace Game.Entities
 
         public AreaTriggerCreateProperties GetCreateProperties() { return _areaTriggerCreateProperties; }
 
+        public override ObjectGuid GetCreatorGUID() { return GetCasterGuid(); }
         public override ObjectGuid GetOwnerGUID() { return GetCasterGuid(); }
         public ObjectGuid GetCasterGuid() { return m_areaTriggerData.Caster; }