fix(infra): pin virtio-container-disk to v1.8.2 (containerd 2.1 manifest fix)

KubeVirt v1.4.0 + RKE2 containerd 2.1.5 cannot pull
quay.io/kubevirt/virtio-container-disk:latest:
  rpc error: code = Unimplemented
  desc = failed to pull and unpack image: not implemented:
  media type "application/vnd.docker.distribution.manifest.v1+prettyjws"
  is no longer supported since containerd v2.1, please rebuild the image as
  "application/vnd.docker.distribution.manifest.v2+json" or
  "application/vnd.oci.image.manifest.v1+json"

The :latest tag was last rebuilt with the v1 manifest schema. Tagged versions
v1.6.5+, v1.7.3, v1.8.2 are rebuilt with v2/OCI manifests.

Pinning to v1.8.2 (newest available, contains current Windows VirtIO drivers).
The image only contains the Windows VirtIO driver ISO mounted as a CDROM —
not the KubeVirt runtime — so it is decoupled from the cluster KubeVirt
version.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

apps/kubevirt-vms/ci1.yaml

@@ -367,7 +367,14 @@ spec:
             claimName: windows-server-2025-iso
         - name: virtio-drivers
           containerDisk:
-            image: quay.io/kubevirt/virtio-container-disk
+            # Pinned to v1.8.2 (latest stable as of 2026-05-08).
+            # The :latest tag uses Docker manifest v1 schema which containerd
+            # 2.1 (RKE2 v1.34.5) refuses to pull with:
+            #   "media type application/vnd.docker.distribution.manifest.v1+prettyjws
+            #    is no longer supported since containerd v2.1"
+            # v1.8.2 is rebuilt with manifest v2/OCI and works on containerd 2.1.
+            # Bump available: https://quay.io/repository/kubevirt/virtio-container-disk?tab=tags
+            image: quay.io/kubevirt/virtio-container-disk:v1.8.2
         - name: sysprep
           sysprep:
             configMap: