Use deploy-via-container

This will cause us to run through the ostree-native container
stack when generating the disk images.

Today for RHCOS we're using the "custom origin" stuff which
lets us inject metadata about the built source, but rpm-ostree
doesn't understand it.

With this in the future (particularly after coreos/coreos-assembler#2685)
`rpm-ostree status` will show the booted container and *understand it*.

We'll have the digest of the OCI archive at least...though
that may get changed if it gets converted to docker v2s2 when pushing
to a registry...

Now in the future what we want is to entirely rework our build
pipeline like this: coreos/coreos-assembler#2685

image-c9s.yaml

@@ -1,6 +1,9 @@
 # See https://github.com/coreos/coreos-assembler/pull/298
 size: 16
 
+# We default to a container image
+deploy-via-container: true
+
 # Disable networking by default on firstboot. We can drop this once cosa stops
 # defaulting to `ip=dhcp,dhcp6 rd.neednet=1` when it doesn't see this key.
 ignition-network-kcmdline: []

image-rhel-9.2.yaml

@@ -1,6 +1,9 @@
 # See https://github.com/coreos/coreos-assembler/pull/298
 size: 16
 
+# We default to a container image
+deploy-via-container: true
+
 # Disable networking by default on firstboot. We can drop this once cosa stops
 # defaulting to `ip=dhcp,dhcp6 rd.neednet=1` when it doesn't see this key.
 ignition-network-kcmdline: []