Add KVM hypervisor playbook to contrib

Optional Ansible playbook for preparing a host for running Kargo.
This includes creation of a user account, some basic packages,
and sysctl values required to allow CNI networking on a libvirt network.

tests/cloud_playbooks/delete-gce.yml

@@ -21,12 +21,14 @@
     - name: delete gce instances
       gce:
         instance_names: "{{instance_names}}"
-        image: "{{ cloud_image }}"
+        image: "{{ cloud_image | default(omit) }}"
         service_account_email: "{{ gce_service_account_email }}"
         pem_file: "{{ gce_pem_file | default(omit)}}"
         credentials_file: "{{gce_credentials_file | default(omit)}}"
         project_id: "{{ gce_project_id }}"
         zone: "{{cloud_region | default('europe-west1-b')}}"
-        metadata: '{"test_id": "{{test_id}}", "network": "{{kube_network_plugin}}"}'
         state: 'absent'
+      async: 120
+      poll: 3
+      retries: 3
       register: gce