Code review comment for autopkgtest-cloud:more-fail-strings

Probably not a terrible idea to pass `--debug` all the time to be honest. It can be really hard or time consuming to debug autopkgtest failures and maybe having all the available info up front would help with that.

I think those changes did work at the time; I would merge them and make sure that the infinite retries stopped happening on their own (as a result of the new code). I wouldn't delete things from the queue manually in this kind of case.