Fix sorting issues/mrs by votes on the groups page

Closes #14394 

The `non_archived` scope applied here https://gitlab.com/gitlab-org/gitlab-ce/blob/master/app/controllers/concerns/issues_action.rb#L5 overrides the previous `ORDER BY` applied inside the IssuesFinder, with the default scope of the Project model, resulting in SQL errors.

```ruby
Issue.reorder(created_at: :desc).joins(:project).to_sql
=> "SELECT issues.* 
    FROM issues INNER JOIN projects ON projects.id = issues.project_id
    ORDER BY issues.created_at DESC"

Issue.reorder(created_at: :desc).joins(:project).merge(Project.non_archived).to_sql
=> "SELECT issues.* 
    FROM issues INNER JOIN projects ON projects.id = issues.project_id 
    WHERE projects.archived = 'f'
    ORDER BY projects.id DESC"

Issue.reorder(created_at: :desc).joins(:project).merge(Project.non_archived.only(:where)).to_sql
=> "SELECT issues.* 
    FROM issues INNER JOIN projects ON projects.id = issues.project_id 
    WHERE projects.archived = 'f'
    ORDER BY issues.created_at DESC"
```

/cc @yorickpeterse 

See merge request !3333