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
Core/LFR: Fix a theoretical error with item_level
Despite the check never happening (player->GetAverageItemLevel() < 0 is impossible), it is more efficient.
Also improves codestyle consistency. Original fix by @emsy.
Merge pull request #11616 from Ascathor/master

Core/LFR: Fix a theoretical error with item_level
Merge branch 'master' of https://github.com/TrinityCore/TrinityCore
[TW217] - Drop unused code.
[TW218] - Core/Scripts: Black Temple - Don't allow the Shade of Akama event to be started a second time if it's already done
[TW219] - DB/SQL: Correct a criteria_id typo at Set Us Up the Bomb SQL
[TW220] Core/Spells: Attempt to hack fix Shadowform stucking issue

based on garyfisher's hack
[TW221] - Core/Scripts: Implement I could say that this cache was rare achievement from Hodir
[TW222] - Core/Scripts: Prevent multiple Twilight Corrupters from being summoned

Refers to http://www.truewow.org/bugs/view.php?id=228
Merge branch 'master' of https://github.com/TrueWoW/TrinityCore