Run partprobe after Ignition partition changes

[pothos]

This adds coreos/ignition#1717 as downstream
patch to fix flatcar/Flatcar#1194

How to use

Backport to Stable after some time?

Testing done

In Jenkins and manually with:

variant: flatcar
version: 1.0.0
storage:
  disks:
  - device: /dev/vda
    partitions:
    - label: VAR
      number: 10
      size_mib: 1
  filesystems:
  - device: /dev/disk/by-partlabel/VAR
    format: vfat
    path: /var
    label: var
    with_mount_unit: true

• Changelog entries added in the respective changelog/ directory (user-facing change, bug fix, security fix, update)
• Inspected CI output for image differences: /boot and /usr size, packages, list files for any missing binaries, kernel modules, config files, kernel modules, etc.

[github-actions]

Build action triggered: https://github.com/flatcar/scripts/actions/runs/6381754978

[pothos]

cl.disk.raid0.root and cl.disk.raid1.root failed initially but this is fixed (forgot to add partprobe to the initrd) and passes in Jenkins, the GitHub Actions have to catch up.

[pothos]

I think I'll backport it to Beta which will be the next Stable.

[pothos]

Backported down to flatcar-3602