The role itself handles the certificate generation and the
download of a pre-built amphora image by default, so there
is no need to do it in the AIO bootstrap. Also, several of
the overrides implemented are the same as the defaults, or
break the role execution, so we remove them to allow the
role defaults to be used instead.
Depends-On: https://review.openstack.org/619179
Change-Id: If261478ce83b82e16da954e229bf4e7590ddcd4d
e55960fe30