Since gerrit #24377 / c55f4069dc6ad198425e8e26cf05ca8be3b578b8 registration from LDAP user don't work anymore with only number
Login from Ldap or Openid connect will be allowed with only numbers if Unix users are not enabled in the platform.
In the case login with only numbers are already on the platform, they will be renamed at the first login after the changes with additional "tlp-"
prefix. The user will be warned about his login update.