When desktop-preinstalled image options were added in
38157b3748, for the raspi subarch, the
options listed there were not scoped for raspi subarch. This results
in those options getting also applied for the HYPERV
ubuntu:desktop-preinstalled image.
Thus scope the newly added options under raspi subarch case only.
(cherry picked from commit 1c7d688319)
LP: #1901846