fix: Initiatives error 500 when single initiative type

[AyakorK]

🎩 Description

There was some misconfigurations and also an error 500 when we were trying to get to the inititatives front-office page when we had only one initiative_type

Testing

Initial local setup :

• Run your bundle exec rails console
• Clear all your initiatives by running Decidim::Initiative.delete_all
• Clean all your initiatives_type by running Decidim::InitiativesType.delete_all

Example:

• Log in as admin
• Access Backoffice
• Go to initiatives
• Create a new initiative type
• Configure the signatures
• Go to front office and access the page
• Make sure you can create a new initiative
• Validate it through the back-office
• Use another account to vote for your new initiative
• Make sure everything works correctly

📌 Related Issues

• Fixes #450

Tasks

• Remove deprecated files
• Remove deprecated locales
• Add new locales linked to the new feature of the new workflow

[Stef-Rousset]

LGTM !