How would you “break” a Linux installation for a hands-on job applicant test?

I would break it just like the most common problem scenarios my enterprise runs into on a frequent basis.

Then watch how they approach the problem. They may fix it, and if so, great!

If not, that's OK too.

The key is to watch how they work. Do they know how to do that work?

Many of us can just get our Linux fixed. Might take a while, may have to learn a new thing, whatever.

That's what you should be looking for. People who can run it, and when there are bumps in the road, get past them, improve and share with others.

I would go to google and download some scripts.

Small RAM, disable swap.