Remove monitored_host 'if'

this if is superficial, since this variable is equal to host_ips
the host_ips variable is always set so we don't need to check it.

salt/monitoring/prometheus/prometheus.yml

@@ -13,7 +13,6 @@ alerting:
 rule_files:
     - /etc/prometheus/rules.yml
 
-{% if grains.get('monitored_hosts') %}
 scrape_configs:
   - job_name: hanadb
     static_configs:
@@ -36,4 +35,3 @@ scrape_configs:
         {% for ip in grains['monitored_hosts'] %}
         - "{{ ip }}:9002" # 9002: ha_cluster_exporter metrics
         {% endfor %}
-{% endif %}