Merge branch 'add_top_nth_metrics' into 'master'

Add top 15 prometheus metrics for gitlab exporter

See merge request archlinux/infrastructure!590

roles/prometheus_exporters/defaults/main.yml

@@ -4,3 +4,5 @@ gitlab_runner_exporter_port: '9252'
 
 prometheus_mysqld_user: mysqld_exporter
 prometheus_mysqld_exporter_port: '9104'
+
+gitlab_exporter_top_nth: 15

roles/prometheus_exporters/templates/gitlab-exporter.conf.j2

 GITLAB_EXPORTER_GITLAB_TOKEN={{ vault_gitlab_gitlab_exporter_token }}
+GITLAB_EXPORTER_TOP_NTH={{ gitlab_exporter_top_nth }}
 GITLAB_EXPORTER_GITLAB_API_URL=https://gitlab.archlinux.org/api/graphql