[ci_gen_kustomize] Do ctlplane assertion only if hosts are present

roles/ci_gen_kustomize_values/tasks/edpm_core_asserts.yml

@@ -28,7 +28,7 @@
 
 - name: Ensure the required baremetal host parameters are configured.
   when:
-    - cifmw_baremetal_hosts is defined
+    - cifmw_baremetal_hosts | default({}) | length > 0
   ansible.builtin.assert:
     that:
       - cifmw_ci_gen_kustomize_values_ctlplane_interface is defined