Fix two zombie bugs

[IProduceWidgets]

About the PR

I identified two bugs with zombies and fixed them.

• Vox health regen from Give vox health regen for poison below 20 damage #33722 was the same strength as the poisoning effect from the PendingZombieComponent meaning Vox would never naturally succumb to the virus. This is bad because it prevents zombies from snowballing, but also because it means Vox could be II forever with no issues which was not intended. Solution: make the poison effect from zombie virus slightly stronger to compensate.
• All zombies were erroneously initialized with the grace period of Initial Infected. This made the zombie virus really really slow by letting anyone bit by a zombie wait 15 minutes before they start taking damage. Solution: Non-Initial Infected zombies no longer get a grace period.

Why / Balance

I squash bug.
This will make zombies virus scarier and faster.
It only matters if you survive a fight with a zombie.

Technical details

Media

Requirements

• I have read and am following the Pull Request and Changelog Guidelines.
• I have added media to this PR or it does not require an ingame showcase.

Breaking changes

Changelog

🆑

• fix: Vox are no longer immune to the zombie virus under certain circumstances
• fix: The zombie virus no longer provides non-Initial Infected an undue grace period before poisoning them.

[pheenty]

Buffing it two times is definitely not "make it slightly stronger", I don't even think Vox being kinda immune to it is an issue, yet the second fix is nice