Scripts/Serpentshrine Cavern: Update Karathress & instance script - #31933

Changes proposed:

Instance:

• Re-handle Scalding Water \ Frenzy Water using spell scripts

Karathress:

• Handle respawn & spawn of fathom guards using spawn groups
• Use Cataclysmic Bolt only if more than one player is engaged
• Re-handle Blessing of Tides implementation
• Add correct Berserk spell
• Despawn summons and all creatures including boss after wipe
• Create base AI for fathom guards
• Update Cyclone's movement implementation

Issues addressed:

none

Tests performed:

builds, tested in-game