Rework prometheus blackbox monitoring configuration

* Use scrape_config_files correctly
 * Do not separate prometheus and blackbox exporter nodes
 * Add a http_2xx_selfsigned module for self-signed certs
 * Monitor missing services
 * Switch from CRLF to LF in prometheus.config.j2

ansible/roles/blackbox-exporter/templates/blackbox.config.j2

@@ -8,6 +8,11 @@ modules:
       preferred_ip_protocol: "ip4"
       ip_protocol_fallback: true
 {% endif %}
+  http_2xx_selfsigned:
+    prober: http
+    http:
+      tls_config:
+        insecure_skip_verify: true
   http_post_2xx:
     prober: http
 {% if inventory_hostname == 'check.home.arpa' %}