Addresses registration side effects observed on simultanous clients login (#647)

Every client UI session gets their own registration layout instance, such that
the observed registration failures due to race conditions are gone.

Author: sven1103

identity/src/main/java/life/qbic/identity/application/user/registration/Registration.java

@@ -20,8 +20,6 @@
 import life.qbic.identity.application.user.policy.directive.WhenUserRegisteredSendConfirmationEmail;
 import life.qbic.identity.application.user.policy.directive.WhenUserRegisteredSubmitIntegrationEvent;
 import life.qbic.identity.application.user.registration.EmailAddressConfirmation;
-import life.qbic.identity.application.user.registration.RegisterUserInput;
-import life.qbic.identity.application.user.registration.Registration;
 import life.qbic.identity.domain.repository.UserDataStorage;
 import life.qbic.identity.domain.repository.UserRepository;
 import life.qbic.infrastructure.email.EmailServiceProvider;
@@ -114,18 +112,6 @@ public PasswordResetInput passwordResetInput(IdentityService identityService) {
     return new PasswordResetRequest(identityService);
   }
 
-  /**
-   * Creates the registration use case.
-   *
-   * @param identityService the user registration services used by this use case
-   * @return the use case input
-   * @since 1.0.0
-   */
-  @Bean
-  public RegisterUserInput registerUserInput(IdentityService identityService) {
-    return new Registration(identityService);
-  }
-
   @Bean
   public UserInformationService userInformationService(UserRepository userRepository) {
     return new BasicUserInformationService(userRepository);