Remove repository tests, usages of registration dto used in repo

web/backend/Features/Features.Auth/Dtos/UserRegistrationDto.cs

@@ -1,12 +0,0 @@
-namespace Features.Auth.Dtos;
-
-/// <summary>Data required to persist a new user account and its initial credential.</summary>
-/// <param name="PasswordHash">The already-hashed password; never a plaintext value.</param>
-public record UserRegistrationDto(
-    string Username,
-    string FirstName,
-    string LastName,
-    string Email,
-    DateTime DateOfBirth,
-    string PasswordHash
-);