[BUU] Fully enable admin_style_v3

[RachL]

⚠ Please use clockify code #7198 Back Office Uplift (Product) while reviewing or working on this task.

TO BE RELEASED On September 3rd
(see schedule)

Description

- As a: super admin
- On page: /admin/feature-toggle/features
- I want to be able to do: See that on top of the admin and new users groups, the toggle is also activated for 100% of users

Acceptance Criteria & Tests

1. Before the PR only admins + new user + 75% + dedicated actors eventually should have had access
2. After: feature is fully enabled

We will trust flipper to work on this one