Explicitly set the serial line for grub to avoid auto probing which may result in a hang.
With version 10.4.0 of cloud regionsrv-client a general way to handle billing model switches has been implemented. This supersedes the previous Azure specific implementation. In addition a billing model change feature is being introduced in GCE. Enable billing model switches in GCE using the new implementation and switch Azure to the new implementation. Feature is not supported for 3rd party listings (Marketplace images) or when no PAYG equivalent exists.
Do not allow root to login via ssh using a password. While we already have measures in place to make it difficult to setup password based login via ssh, this adds another layer addressing the root user. Cloud instances should only used key based login.
Depending on the protocol version for SSH we need to set either ChallengeResponseAuthentication or KbdInteractiveAuthentication to "no". Prior to this change we only set ChallengeResponseAuthentication allowing password based login when the SSHv2 protocol is used. We now modify newer config files appropriately.