Allow opting out of test output "simplification"

[benjyw]

We strip chroot paths from test output, as they are an implementation detail that users will find confusing, but that leak into the paths that tests see.

However sometimes that can go awry and the regex we use will match more than intended. So we should offer an escape hatch, and then disable this output rewriting in the pants repo itself, where we typically do want to see the chroot paths, as they are precisely what we may be debugging!

[tgolsson]

I have a PR that changes this (and fixes the overeager replacements)!