The /dev/vdb -> /var partitioning in cookbooks/base/overlay.bu was merged
into every project's main spec, so it ended up in the production/test
ignition even though the second disk (var.qcow2) only exists in the libvirt
dev/test VM. A real host should not have `base` blindly repartition /dev/vdb.
Move it to local.bu / local.bu.template, which feeds local.ign and is merged
into both fcos-dev.ign and fcos-test.ign but is never part of the shipped
package. This restores partitioning for all VMs while keeping it out of
production.
Also add the overlay-examples.bu merge mechanism to scripts/common.mk (mirror
of the existing overlay.bu merge) for future per-project example overlays, and
whitelist overlay-examples.bu in .gitignore.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>