If dontCreateUser is set, do nothing with the user

Previously, this case was logged as "Not creating user {}, and not setting its password or authorizing keys" - but due to a missing else clause, it immediately went on to try and change the password/authorized keys file.

Note that the logic in this function is confusing and the reasons for actions is not clear; it could benefit from a clear explanation of what it needs to achieve, and a code cleanup and review to make sure it works correctly.