create_testing_networks_groups.yaml

---
- hosts: all
  become: true
  gather_facts: false
  tasks:
    - name: create testing group on webservers
      group:
        name: testing
        state: present
        gid: 3030
      when: inventory_hostname in groups['webservers']
    - name: create networks group on prod nodes
      group:
        name: networks
        state: present
        gid: 4040
      when: inventory_hostname in groups['prod']
...