test(turbopack): Configure HMR benchmark (#80219)
### What?
Configure HMR benchmark. I'm not sure if this benchmark would be stable enough, but let's try.
I'll remove this from the automated benchmark later this week if it turns out to be flaky.
### Why?
x-ref: https://vercel.slack.com/archives/C06PPGZ0FD3/p1748943158878159
### How?
Closes PACK-4758
