Scripts/Quests: Fix Red Snapper - Very Tasty! GOb

Fix 'School of Red Snapper' now disappear correctly when using 'Draenei Fishing Net', the bug is caused because the GameObject is SpellFocus type.

Fix: #1673
It is because in SpellCastResult not exists GetHitGObj() and with FindGameObject() located the top of the list and could produce bug a nearby on gameobject invalid