Scripts/Ulduar: Fix Algalon the Observer outro phase(fixes kill credit and some achieves).
DB/Creature: spawn Stabled Argent Warhorse

By Foldor, closes #11479, updates #11043
DB/Creature: Fix another trigger visible to players
DB/Creature: Delete some double spawns

Updates #1515
DB/Reputation: Fix Oracle and Frenzyheart Tribe reputation

Closes #11106
Merge branch 'master' of https://github.com/TrinityCore/TrinityCore