Cleanup packages list

Quite a few packages are explicitly listed in config/chroot_local-packageslists/tails-common.list to satisfy dependencies of custom packages we now ship in our APT repository. Assuming these custom packages have proper dependency information embedded, this should not be necessary… and is very likely to quickly become outdated wrt. the actual current dependencies.

So, we should drop this duplicate information, compare the list of packages installed in the resulting ISO, and fix our custom packages if needed.

Feature Branch: bugfix/6073-cleanup-packages-list

Original created by @tails on 6073 (Redmine)