Fixes for welders and lockers

Welders used to start welding lockers even when off. They didn't finish, but now they won't even begin.

I also tried to tackle https://github.com/tgstation/-tg-station/issues/4187. I am not happy with how I fixed it, but it should sort of work, at least in normal circumstances. do_after() may need a rewrite to fix the issue "properly".