[Task]: Rename some GitHub labels

[diox]

Description

https://github.com/mozilla/addons/issues/14820 removed obsolete labels on mozilla/addons repos, we agreed to simplify some of the remaining ones by renaming them according to the spreadsheet.

Acceptance Criteria

  ### Acceptance Criteria
  - [ ] Label `state:verified_fixed` is renamed to `qa:verified`
  - [ ] Label `env:local_dev` is renamed to `local_dev` (`local_dev` already exists though!)
  - [ ] Label `type:prod_bug` is renamed to ??
  - [ ] Label `state:stale` is renamed to `stale` ? (wasn't in the spreadsheet, noted in https://github.com/mozilla/addons/pull/14824)

Checks

• [X] If the issue is ready to work on, I have removed the "needs:info" label.

┆Issue is synchronized with this Jira Task