User password is stored in a system space is a form of hash when
'chap-sha1' auth type is set, and in a form of hash with salt when
'pap-sha256' is set.

Now, if a user is set inside config, and the current auth type is
different from the type the users password is stored in, the password
hash will be regenerated.

Part of #8967

NO_DOC=documentation request will be filed manually for the whole
       credentials