Fix in https://github.com/twentyhq/twenty/pull/22965 was wrong, 440px
wide is the new intended width for both signup forms.
This PR reverts + does the correct fix.

See figma as source of truth
https://www.figma.com/design/xt8O9mFeLl46C5InWwoMrN/Twenty?node-id=1633-94880&p=f&m=dev

## Before
<img width="431" height="450" alt="Screenshot 2026-07-16 at 18 14 26"
src="https://github.com/user-attachments/assets/3f8788e1-3764-4326-867a-973a98e48007"
/>

## After
<img width="1030" height="898" alt="Screenshot 2026-07-17 at 08 24 38"
src="https://github.com/user-attachments/assets/42e03215-f32c-4f61-8f2d-1b8ff966d31c"
/>
<img width="1028" height="900" alt="Screenshot 2026-07-17 at 08 24 25"
src="https://github.com/user-attachments/assets/3a49142a-dc52-4097-96d2-05a4e641f574"
/>