Set default for n_timeout_ticks var

defaults/main.yml

@@ -4,3 +4,4 @@ paas_ci_orchestrator_url: https://paas.cloud.infn.it/orchestrator
 paas_ci_iam_group: admins/cicd 
 paas_ci_workdir: "{{ lookup('env','WORKSPACE') }}"        
 paas_ci_scan_script_path: "{{ paas_ci_workdir }}/scan.py"
+n_timeout_ticks: 12
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