Added hot-reload to prometheus.

Author: samoht9277

infra/ansible/playbooks/templates/services/prometheus.service.j2

@@ -9,6 +9,7 @@ Group=prometheus
 Type=simple
 ExecStart=/usr/local/bin/prometheus \
     --config.file=/etc/prometheus/prometheus.yml \
+    --web.enable-lifecycle \
     --storage.tsdb.path=/var/lib/prometheus \
     --web.console.templates=/etc/prometheus/consoles \
     --web.console.libraries=/etc/prometheus/console_libraries