Stop login retrying if username is invalid

After an unsuccessful login using a password from the password file,
when the API returns 'NotExists' or 'Invalid', repeating the login
process with a new password supplied from the terminal by the user
will not remedy the situation.  Raise NoUsername exception instead,
as the problem is a config issue.

Bug: 73533
Change-Id: I4276c47be2e34fb6aba3490e2b029f9276b7d03a
Merge "Stop login retrying if username is invalid"