Removed deprecated roles on Associates in Business Units

Following the deprecation announcement on 2 May 2023, we have now fully removed the deprecated AssociateRole enum with Buyer and Admin values as well as the roles field on Associate and AssociateDraft.

The deprecated functionality has been replaced by the Associate Roles API. Use the associateRoleAssignments property to assign Associate Roles to Associates.

Changes:

• [API] Removed roles from Associate and AssociateDraft.
• [API] Removed AssociateRole enum with Buyer and Admin values.