counters: add a prometheus job to read the new metrics end-point

Related to T3164

Test Plan

diff origin/production/counters0.internal.staging.swh.network current/counters0.internal.staging.swh.network
*******************************************
  Concat::Fragment[nginx-swh-counters-default-header] =>
   parameters =>
     content =>
      @@ -1,5 +1,5 @@
       # MANAGED BY PUPPET
       server {
      -  listen 127.0.0.1:5011 default_server;
      +  listen 0.0.0.0:5011 default_server;
      _
      _
*******************************************
  Concat::Fragment[nginx-swh-counters-header] =>
   parameters =>
     content =>
      @@ -1,5 +1,5 @@
       # MANAGED BY PUPPET
       server {
      -  listen 127.0.0.1:5011 deferred;
      +  listen 0.0.0.0:5011 deferred;
      _
      _
*******************************************
  Concat_fragment[nginx-swh-counters-default-header] =>
   parameters =>
     content =>
      @@ -1,5 +1,5 @@
       # MANAGED BY PUPPET
       server {
      -  listen 127.0.0.1:5011 default_server;
      +  listen 0.0.0.0:5011 default_server;
      _
      _
*******************************************
  Concat_fragment[nginx-swh-counters-header] =>
   parameters =>
     content =>
      @@ -1,5 +1,5 @@
       # MANAGED BY PUPPET
       server {
      -  listen 127.0.0.1:5011 deferred;
      +  listen 0.0.0.0:5011 deferred;
      _
      _
*******************************************
  Nginx::Resource::Server[nginx-swh-counters-default] =>
   parameters =>
     listen_ip =>
      - 127.0.0.1
      + 0.0.0.0
*******************************************
  Nginx::Resource::Server[nginx-swh-counters] =>
   parameters =>
     listen_ip =>
      - 127.0.0.1
      + 0.0.0.0
*******************************************
+ Profile::Prometheus::Export_scrape_config[swh-counters_counters0.internal.staging.swh.network] =>
   parameters =>
     "job": "swh-counters",
     "labels": {
     },
     "metrics_path": "/metrics",
     "scheme": "http",
     "target": "counters0.internal.staging.swh.network:"
*******************************************
*** End octocatalog-diff on counters0.internal.staging.swh.network

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Migrated from D5324 (view on Phabricator)