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/DynamicObject.cs

@@ -305,6 +305,7 @@ namespace Game.Entities
         public Unit GetCaster() { return _caster; }
         public uint GetSpellId() { return m_dynamicObjectData.SpellID; }
         public ObjectGuid GetCasterGUID() { return m_dynamicObjectData.Caster; }
+        public override ObjectGuid GetCreatorGUID() { return GetCasterGUID(); }
         public override ObjectGuid GetOwnerGUID() { return GetCasterGUID(); }
         public float GetRadius() { return m_dynamicObjectData.Radius; }