[PetraAI] - Teach PetraAI to fear fire.
In r24608 / rP24608, fire damage was introduced for the Iberian fire ship (and the Theban fire raiser), this adds that damage type to the config of PetraAI.
Poison (r24508 / rP24508) is only used in Status Effects (which PetraAI doesn't understand anyway) so is not added.
Differential revision: D3432
Reviewed by: @Angen