cks: set CDROM volume label when building the binaries ISO

The CKS nodes locate the binaries ISO purely by its ISO 9660 volume label:

  output=`blkid -o device -t LABEL=CDROM`   (conf/k8s-control-node.yml)

but create-kubernetes-binaries-iso.sh invoked mkisofs without -V, relying on
the tool's default volume ID. That default is not portable:

  genisoimage / cdrkit (Debian, Ubuntu)  -> CDROM
  xorriso mkisofs compat mode (EL8+)     -> ISOIMAGE

genisoimage has not been available since EL8, where mkisofs is provided by
xorriso, so an ISO built on EL8/EL9/EL10 gets LABEL="ISOIMAGE". The nodes then
never mount it, loop on "Waiting for Binaries directory /mnt/k8sdisk/ to be
available" until the offline install times out, and silently fall through to
installing from the Internet instead of using the pinned ISO contents.

Pass -V CDROM explicitly so the output no longer depends on which ISO tool the
build host happens to provide. This is a no-op on hosts where the script works
today, since CDROM is already the genisoimage default.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

Author: kiranchavala

scripts/util/create-kubernetes-binaries-iso.sh

@@ -148,6 +148,10 @@ chmod ${kubeadm_file_permissions} "${working_dir}/k8s/kubeadm"
 echo "Updating imagePullPolicy to IfNotPresent in yaml files..."
 sed -i "s/imagePullPolicy:.*/imagePullPolicy: IfNotPresent/g" ${working_dir}/*.yaml
 
-mkisofs -o "${output_dir}/${build_name}" -J -R -l "${iso_dir}"
+# The volume label must be CDROM: the CKS nodes locate this ISO with
+# "blkid -o device -t LABEL=CDROM" (see conf/k8s-control-node.yml). Do not rely on the
+# tool default -- genisoimage defaults to CDROM but xorriso's mkisofs compatibility mode
+# (the only mkisofs available on EL8+) defaults to ISOIMAGE, which the nodes never find.
+mkisofs -V CDROM -o "${output_dir}/${build_name}" -J -R -l "${iso_dir}"
 
 rm -rf "${iso_dir}"