feat: Remove 'unique' property from List schema (QuestionField)

[DafyddLlyr]

What does this PR do?

• Removes the QuestionField["unique"] property
• Please see feat: List component - First iteration of a residential units schema #3222 for further context

Why this change?

• It's not currently used or necessary for existing schemas
• There's likely better ways of handling this (e.g. pre-populating forms, not putting the onus on the user to manage this)
• It's only being enforced via the UI, and not in the schema currently

[github-actions]

Removed vultr server and associated DNS entries