[PM-3777[PM-3633] Update minimum KDF iterations when creating new User record (#3687)

* Updated minimum iterations on new Users to the default.

* Fixed test I missed.

test/Identity.Test/Controllers/AccountsControllerTests.cs

@@ -58,7 +58,7 @@ public class AccountsControllerTests : IDisposable
         var userKdfInfo = new UserKdfInformation
         {
             Kdf = KdfType.PBKDF2_SHA256,
-            KdfIterations = 5000
+            KdfIterations = AuthConstants.PBKDF2_ITERATIONS.Default
         };
         _userRepository.GetKdfInformationByEmailAsync(Arg.Any<string>()).Returns(Task.FromResult(userKdfInfo));