How to drop a project

Projects are often dropped due to inactivity. We should not keep projects where translations do not reach end users. See also https://phabricator.wikimedia.org/T228072

Removal checklist

• Inform the maintainers (if possible)
• Update in the translatewiki repo:
  • Remove from repoconfig.yaml
  • Remove from TranslateSettings.php (keep namespace!)
  • Remove group yaml and associated validators if any
  • Remove from aggregate groups if any
• Update in the wiki:
  • Remove from Group descriptions
  • Update Translating:X to say it is discontinued by adding {{Discontinued project}} on top of the page.
  • Update Category:X to change category from Category:Supported projects to Category:Formerly supported projects
  • Mention the removal in News
  • Update Template:User X to say "helped translating" instead of "helps translating"
  • Update Category:X translators to change category from Category:Users by project to Category:Users by former project
  • Update Category:Support requests for X to change category from Category:Support requests to Category:Support requests for formerly supported projects