DB/SAI: Added SAI for the second part of mobs before the gunship battle
Scripts/Freya: Fix Lumberjacked Achieve

Closes #13435
Fixes #8166
Scripts/Ulduar: Fix Kologarn's arms being despawned before they're used to access the rubble spawning triggers
DB/Item: Northrend Mystery Gem Pouch (3.3.5)

* This is probably only valid for 3.3.5 as item is marked as no longer available in game and last comment on wowhead is from 4.1.0 saying item is now worthless, was added in 3.2
* Remove northrend rare gems for emblem of heroism from Lhara and replace with this item
DB/Misc: Zone Wide Texts
DB/Misc: Short John Mithril / Arena Treasure Chest

* Remove permament spawn of Arena Treasure Chest 
* Script Short John Mithril to start wp at start of event, say his 2 lines (1st zone wide) and summon Arena Treasure Chest