Make clean does not work in staging or prod environments

[emkll]

Steps to reproduce, on a production install:

cd /usr/share/securedrop-workstation-dom0-config/
make clean

Due to changes in how files are provisioned with RPMs, we will need a staging/production specific clean makefile target. Removing the yum package will remove the provisioning logic, but will not delete files. The following commands in a makefile target work locally, we could also add this to securedrop-admin with a prompt/warning) but does not delete config files config.json and sd-journalist.sec (both in /usr/share/securedrop-workstation-dom0-config and /srv/salt/sd), which we could delete after uninstalling the dom0-config package).

  sudo qubesctl --show-output state.sls sd-clean-default-dispvm
  $(MAKE) destroy-all
  sudo qubesctl --show-output --skip-dom0 --targets whonix-gw-15 state.sls sd-clean-whonix
  sudo qubesctl --show-output state.sls sd-clean-all
  sudo dnf -y -q remove securedrop-workstation-dom0-config 2>/dev/null || true

This mostly impacts testing, as in production contexts, we should recommend properly disposing of (destroying) the storage