[Blueprint servercloud-r-fastpath-install] fast server install for cloud-image like experience

[Scott Moser]

Blueprint changed by Scott Moser:

Whiteboard changed:
  User Stories:
  Rocky runs a MAAS cluster.  The nodes have frequent turnover and installation time is time lost.  Faster installation means higher usage time.
  
  Assumptions:
  The fast path installer is intended to only support simplistic cloud-image-like installation.  Users wishing for for more complex partition layout may need to use the debian installer path.
  
  Risks:
  bootloader installation is non-trivial.  The debian installer does a good job of doing this.  If we can't re-use that logic we risk failing to boot.  UEFI boot is also complex and may be required for some systems.
  
  Test Plans:
- This code path will be used in the Ubuntu openstack CI framework to help it install faster.  That will prove at least one functional path.
+ This code path will be used in the Ubuntu openstack CI framework to help it install faster.  That will prove at least one functional path.  Additionally, the code is testable inside kvm with a cloud-image serving as the bootable system and installing to a target second disk in the system.
  
  Release Note:
  Nodes installed through MAAS can use the fast path installer to significantly reduce installation time.  It results in a cloud-image like environment with customization available via cloud-init on first boot.

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fast server install for cloud-image like experience
https://blueprints.launchpad.net/ubuntu/+spec/servercloud-r-fastpath-install