text: Title: When creating `sysadmin` user flow aborts, the user is still created
  Body: ## CKAN version
  
  CKAN version: 2.10.3
  Python version: 3.9.6
  OS: Mac
  
  ## Describe the bug
  When creating a `sysadmin` user for an install of CKAN on my local machine and it fails, the user is still created in the user table.
  
  ### Steps to reproduce
  Steps to reproduce the behavior:
  1. With the virtual environment activated, run `ckan sysadmin add <admin>`
  2. There is a prompt to enter an email, enter any email
  3. There is a prompt to enter a password, enter in a password that does NOT meet the criteria (longer than 8 characters)
  4. Confirm the password
  5. There is a prompt with the password criteria which needs to be more than 8 characters and that the user flow has been aborted.
  6. Now re-run `ckan sysadmin add <admin>`
  7. Enter an email
  8. Enter a valid password with at least 8 characters
  9. Confirm the password
  10. Then you should see a note that says:
  ```
  None - {'name': ['That login name is not available.']}
  Aborted!
  ```
  11. Once you create the a sysadmin user, run the app then go to the admin panel and view users to confirm that the first user you tried to create was created even though the user creation flow was aborted.
  
  ### Expected behavior
  
  If the user creation flow was aborted, a user should not be created.
  
  ### Additional details
  
  This is a screenshot of the 2nd time attempting to create a user with the same name which illustrated that the first time it was created even though the user creation flow was aborted.
  ![image](https://github.com/ckan/ckan/assets/4407063/e4fd39fa-5b5c-4a42-af58-142dfda8fa7e)
  
  
  