Allow deleted versions to use "Confirm Multiple Versions" action

[chrstinalin]

Fixes: mozilla/addons#1948

Description

Allows deleted, auto-approved versions to be included when using the "Confirm Multiple Versions" action for unlisted add-ons.

Testing

1. Auto-approve an unlisted add-on version.
2. Delete auto-approved version.
3. 'Confirm multiple versions' option should be available, and version itself should be listed among the version options.
   

Checklist

• Add #ISSUENUM at the top of your PR to an existing open issue in the mozilla/addons repository.
• Successfully verified the change locally.
• The change is covered by automated tests, or otherwise indicated why doing so is unnecessary/impossible.
• Add before and after screenshots (Only for changes that impact the UI).