fixes another heist mode breaking bug

vox can never win their inviolate_crew objective due to not having cortical stacks put in them on setup.
i took this code from one_click_antag's create_vox_raider() and edited it slightly.
i was thinking about merging the two procs into one but i will leave that for you to decide.
Merge pull request #5513 from Walter0o/patch-1

fixes another heist mode breaking bug