Core/Players: Fixed trainers still displaying profession skills after learning

Closes #8103
DB/Instance: Fixed mutated abomination regenerating power clientside
Core/Vehicles: Fixed channeled spells being interrupted for passengers when vehicle moves
Core/Vehicles: Fixed power issues

* Regenerate powers only if vehicle has UNIT_FLAG2_REGENERATE_POWER
* Removed old pyrite power hack
* Apply creature_template.ManaMod to all power types

Closes #12141