Some loot corrections

[schell244]

🍰 Pullrequest

Recipe: Mighty Rage Potion -> increase drop chance from 2% to 4%
Big-mouth Clam -> rework loot, add grouping, rework drop chances from mobs
Small Sack of Coins -> add missing loot items (previously only 1 was item in loot table), add gold drop
Cuergo's Hidden Treasure -> group loot items, add gold drop
Cuergo's Gold with Worm -> remove from creature loot table
Core of Earth -> rework drop chances
Pristine Yeti Horn - increase drop chance from 10% to 25% (Quest: Are We There, Yeti?)

Proof

• www.wowhead.com/classic - see links in sql comments

Issues

• fixes loot part of 🐝 [Bug] Cuergo's Gold quest #1340

How2Test

• check drop chances in game

Todo / Checklist

• Gold drop amount of Small Sack of Coins and Cuergo's Hidden Treasure might be imprecise, range/amount was taken from comments of wowhead/videos.