Priest.lua - show duration of self-buff Insanity

Insanity is different since 6.0, such that: when you cast Devouring Plague, you gain the self buff "Shadow Word: Insanity" (132573). For the duration that that buff is active, Mind Flay is transformed into Mind Flay: Insanity (129197). As such the previous debuff spell tracking no longer works with Insanity.

Perhaps there's a way to make this track by adding the change to LibPlayerSpells, but I couldn't see such a thing.