Run Cucumber and Test::Spec tests at tails-persistence-setup Debian package build time

Originally created by @intrigeri on #6441 (Redmine)

We currently skip these tests as the needed testing modules are not in Squeeze. Once we’re based on Wheezy, we can enable them.

Edited May 15, 2020 by intrigeri

To upload designs, you'll need to enable LFS and have an admin enable hashed storage. More information