fix(kubernetes): set fixed 2Gi ephemeral-storage for virt-launcher pod

With PVC-backed persistent disks, the virt-launcher pod no longer needs
ephemeral-storage sized to the full disk. Set a fixed 2Gi allocation
for QEMU runtime needs and proper scheduler behavior.

Assisted-By: Claude <noreply@anthropic.com>
Signed-off-by: Arsolitt <arsolitt@gmail.com>

packages/apps/kubernetes/templates/cluster.yaml

@@ -82,7 +82,7 @@ spec:
               guest: {{ .group.resources.memory }}
             {{- end }}
             resources:
-              {{- include "cozy-lib.resources.sanitize" (list (dict "ephemeral-storage" .group.diskSize) $) | nindent 14 }}
+              {{- include "cozy-lib.resources.sanitize" (list (dict "ephemeral-storage" "2Gi") $) | nindent 14 }}
           evictionStrategy: External
           volumes:
           - name: system