[Merge] ~jchittum/livecd-rootfs:vagrant_slow_boot_workaround_with_null_file into livecd-rootfs:ubuntu/master

[John Chittum]

The proposal to merge ~jchittum/livecd-rootfs:vagrant_slow_boot_workaround_with_null_file into livecd-rootfs:ubuntu/master has been updated.

Description changed to:

addresses https://bugs.launchpad.net/cloud-images/+bug/1874453

Testing:

1. ran a bartender build using my branch of livecd-rootfs
ubuntu-bartender --livecd-rootfs-dir /home/jchittum/dev01/livecd-rootfs --build-provider multipass -- --series focal --project ubuntu-cpc
2. untarred the build
3. added local with
vagrant box add test-focal ./build-output/livecd.ubuntu-cpc.vagrant.box
4. used basic Vagrantfile
  Vagrant.configure("2") do |config|
    config.vm.box = "test-focal"
  end
5. ran vagrant up
6. ensured box booted and was ssh'able
7. ran vagrant destroy
8. added a config for a local serial file:
  Vagrant.configure("2") do |config|
    config.vm.box = "test-focal"
    config.vm.provider "virtualbox" do |vb|
      vb.customize [ "modifyvm", :id, "--uartmode1", "file", File.join(Dir.pwd, "test-console.log") ]
    end
  end
9. ran vagrant up
10. ensured image came up, was ssh'able, and there was a file named "test-console.log" in the same directory as the Vagrantfile that contained serial console logging.

11. repeat but with groovy targets.
ubuntu-bartender --livecd-rootfs-dir /home/jchittum/dev01/livecd-rootfs --build-provider multipass -- --series groovy --project ubuntu-cpc

For more details, see:
https://code.launchpad.net/~jchittum/livecd-rootfs/+git/livecd-rootfs/+merge/389918
-- 
Your team Ubuntu Core Development Team is requested to review the proposed merge of ~jchittum/livecd-rootfs:vagrant_slow_boot_workaround_with_null_file into livecd-rootfs:ubuntu/master.