Cleanup Puppet code after deploys have happened

Some changes in our Puppet codebase have to be run only once (example: removal of some packages or files). These should be cleaned up once we have deployed all changes.

• https://git.tails.boum.org/puppet-tails/log/?h=53_query-gitlab-needs-validation
• https://git.tails.boum.org/puppet-tails/log/?h=55-56_weblate-pull-from-gitlab-push-to-gatekeeper