Add auth section to testlist job

Author: LDiazN

ansible/roles/prometheus/templates/prometheus.yml

@@ -391,6 +391,9 @@ scrape_configs:
       - testlist-ec2.dev.ooni.io
       - testlist-ec2.prod.ooni.io
     scrape_interval: 5s
+    basic_auth:
+      username: 'prom'
+      password: '{{ prometheus_metrics_password }}'
     scheme: http
 
   - job_name: "airflow"