Increase default length of auto generated passwords
Installer/IPA generates passwords for warious purpose:
* KRA
* kerberos master key
* NSSDB password
* temporary passwords during installation
Length of passwords should be increased to 22, ~128bits of entropy, to
be safe nowadays.
https://fedorahosted.org/freeipa/ticket/6116
Reviewed-By: Alexander Bokovoy <abokovoy@redhat.com>