Fix PetraAI not rushing.
A typo in the starting strategy.
Reported by: @marder on http://irclogs.wildfiregames.com/%230ad-dev/2021-11-12-QuakeNet-%230ad-dev.log
Introduced in r25876 / rP25876.
Differential revision: https://code.wildfiregames.com/D4391
Fixes: #6381