Archive config files along with logs

When debugging gate failures, it's useful to know what the config file
looked like in order to replicate issues locally or spot possible errors
at a glance.

This patch makes the cleanup function keep the config files of every
project (if present).

Change-Id: Id8a99c35e9e4370cfb316c5a4aae2899fea3f5bc
Merge "Archive config files along with logs"