mkimage-raw-efi references lower-level serial container dir directly and shouldn't

[deitch]

The pkg mkimage-raw-efi references the specific path of an onboot container:

# Before changing something here please take a look into the
# images/rootfs.yml.in onboot section: the installer should
# precede the storage-init container.
#
# now lets create an edge container
# FIXME: 002-installer? why not linuxkit build?
WORKDIR /eco/media/root-rw/root/containers/onboot/002-installer
COPY runtime.json config.json ./
RUN mv /out rootfs
# hadolint ignore=DL3003
RUN (cd /eco && find . -xdev | grep -v installer.img | sort | cpio --quiet -o -H newc) | gzip > rootfs/installer.img
RUN mv rootfs /out

This even has a FIXME, and comments in the main rootfs.yml.im to change that if you add anything that changes the onboot order.

Similar code exists in mkverification-raw-efi.

Why is this necessary? What can we do to make this cleaner, as it is messy and almost guaranteed to break in odd ways in the future.

@rouming do you know what this does, i.e. its intended behaviour? You have the commit on mkverification-raw-efi and on mkimage-raw-efi.

Maybe there is nothing better, but we should try.