[0447] Correcting drops of items 18969 and 18972

* Correcting drop rates of items to 2.5% and adding to unique group.
* Removing items from Lurking Feral Scar ID:7848
Listed on this mob most likely due to bug with loot tracking software
* Added in correct PreReq quests for the items to drop
Quest 2821 for Item 18969
Quest 2822 for Item 18972
Sources: Wowpedia, Allakhazam (WayBackMachine), Magelo