Start with an empty /etc/machine-id to disable ConditionFirstBoot

The systemd firstboot process does several things, but notably
it runs a preset process.  This means that basically a plain
`RUN systemctl enable foo` won't work unless you *also* write
a preset file for it, and no one will know to do that.

tier-0/manifest.yaml

@@ -2,9 +2,8 @@
 # Modern defaults we want
 boot-location: modules
 tmp-is-dir: true
-# This one at least historically broke compatibility with Anaconda, but
+# https://github.com/CentOS/centos-bootc/issues/167
-# let's use it by default now.
+machineid-compat: true
-machineid-compat: false
 # Be minimal
 recommends: false