fix: proposals filter default order

[Stef-Rousset]

🎩 Description
This removes a no more necessary method that replaced the proposals filter default order chosen by admin with "recent".

📌 Related Issues
Notion card

Testing

1. As an admin, go to a process
2. Go to the configuration of proposals component
3. Select in the "Default proposal sorting" , the "Default" value and update
4. Go to the process public page, go to proposals and see that the Order by filter is set to "Random" (which correspond to the default value, cf screenshot), and not "Recent"
5. As an admin, change the value of the "Default proposal sorting" and update
6. See in the public page that the filter is now set to the new value

Screenshot

[luciegrau]

Tried locally and it works, thank you!