scaleddownapertisimage, ostree: replace minimal by fixedfunction

Rename minimal to fixedfunction to reflects the "Fixed function device scenario" from Apertis Platform Technical Vision.

Also replace in ostree the references to 18.06 and 18.12 releases by v2022 which is the first release version providing fixedfunction images.

Signed-off-by: Frédéric Danis frederic.danis@collabora.com