Revert the pAI invisibility to make them hear speech and visible_message again.

This reverts the pAI part of https://github.com/tgstation/-tg-station/pull/5704
This would reopen #2034 and #5394 but would make pAI able to hear speech and visible_message making them playable again.
The only other quick way to fix it that I could think of was https://github.com/tgstation/-tg-station/pull/6128 but it wasn't accepted.