Hunt for Oldcode: Plasmoid disease does not exist

Created by: ConkerDev

https://github.com/d3athrow/vgstation13/blob/629f35941fb0b109ab257139021734eb386001e4/code/datums/diseases/plasmatoid.dm This disease exists only in the form of a non-functional disease, and an entry in the medical records claiming it makes humans and monkeys require toxin to breathe. We already have plasmamen, and this file was last updated 23 Aug, 2010. I say we remove it.