Define automated checks for monthly L10n maintenance tasks

Current state

Right now, the Localization Engineering team manually runs checks in monthly-maintenance-tasks.md each month to keep /doc-locale in sync with /doc. Some of these checks are repetitive and could be automated, like detecting and deleting orphans i.e. files that exist in translations but not in source: Auto-delete orphaned translated files instead o... (#303))

What we are currently doing manually: removing expired redirects, updating the Argo Redirects component, validating locale builds, and checking sync with source.

Goal

• Figure out which parts of our monthly localization cleanup can run automatically in a scheduled pipeline, similar to how the Technical Writing team does it: https://gitlab.com/gitlab-org/technical-writing/docs-gitlab-com/-/blob/main/doc/tasks.md
• Understand if there is any growing inefficiency in any manual work manual work (the answer could be no) and automate things that make sense

Let's discuss as a team what we should automate first Which checks are safe to run without human review, whether we need locale-specific validations, etc.