Raidboss issue during Bardams Mettle

[MagesBallad]

The warning to run away from boss when you have a tether on the first boss goes off repeatedly instead of being 1 warning, also comes back when the boss charges at you

[xiashtra]

Bardam's Mettle, and specifically the first boss (Garula) tether mechanic, was one of the dungeon mechanics updated for Duty Support in 6.4 and likely doesn't work properly with previous triggers.

Ref. #5117