[Ansible] Aggregate results from multiple hosts into a single var for later use

main.yml

---
- hosts: all
  vars:
    uuids: |
      {%- set o=[] %}
      {%- for i in play_hosts %}
        {%- if o.append(hostvars[i].uuid) %}
        {%- endif %}
      {%- endfor %}
      {{ o }}
  tasks:
    - name: get uuids for existing cluster nodes
      shell: mysql -N -B -u {{ db_user }} -p {{ db_user_password }} -e "SHOW GLOBAL STATUS LIKE 'wsrep_cluster_state_uuid';" | sed 's/\t/,/g' | cut -f2 -d','
      register: maria_cluster_uuids
    - set_fact:
        uuid: "{{ maria_cluster_uuids.stdout }}"
    - debug:
        var: uuids
      run_once: true
      delegate_to: 127.0.0.1