Upate all uniqueness validation to employ UniqueConstraint classes #10361
Description
Proposed Changes
Replace all instances of unique_together under a model Meta class with a list of UniqueConstraint instances defined under constraints. Additionally, and custom overrides of a model's validate_unique() method should be removed where possible.
Justification
UniqueConstraint was introduced in Django 4.0 and allows for conditional evaluation. This should allow us to ditch any custom validate_unique() logic, such as what is currently defined for the Device model. The Django docs also recommend moving away from unique_together in general as it will likely be deprecated in the future.