Merge branch 'zj-add-active-runner-count' into 'master'

Add active runner count

Sometimes it is good to know how many runners are active. This way we could rule out if a large fleet was enabled.

The query takes about 33ms on GitLab.com, so can be safely added.

cc @pcarranza

See merge request !31

lib/gitlab_monitor/database/row_count.rb

@@ -18,7 +18,8 @@ module GitLab
           },
           personal_snippets: { select: :snippets, where: "type='PersonalSnippet'" },
           project_snippets: { select: :snippets, where: "type='ProjectSnippet'" },
-          users: { select: :users }
+          users: { select: :users },
+          active_runners: { select: :ci_runners, where: "active=true AND contacted_at > current_date - 1" }
         }.freeze
 
         def run