fix: skip multus when not defined (#10934)

fix task failure:
TASK [kubernetes-apps/network_plugin/multus : Multus | Start resources] ************************************************
fatal: [hfal12k8n1 -> {{ groups['kube_control_plane'][0] }}]: FAILED! => {"msg": "Error in jmespath.search in json_query filter plugin:\n'ansible.vars.hostvars.HostVarsVars object' has no attribute 'multus_manifest_2'"}

roles/kubernetes-apps/network_plugin/multus/tasks/main.yml

@@ -9,7 +9,7 @@
     state: "latest"
   delegate_to: "{{ groups['kube_control_plane'][0] }}"
   run_once: true
-  with_items: "{{ multus_manifest_1.results + (multus_nodes_list | map('extract', hostvars, 'multus_manifest_2') | list | json_query('[].results')) }}"
+  with_items: "{{ (multus_manifest_1.results | default([])) + (multus_nodes_list | map('extract', hostvars, 'multus_manifest_2.results') | default([]) | list) }}"
   loop_control:
     label: "{{ item.item.name if item != None else 'skipped' }}"
   vars: