Create new dashboard in ElasticSearch for pager load

Overview

~"team::Practices" owns multiple services and one of our goals is to reduce pager load for those services. We need to track the pages we get on each service. All the on-call paging information is inside ElasticSearch.

Proposal

1. Create a new dashboard in ElasticSearch to show page count for each service owned by ~"team::Practices"
2. Embed dashboard in handbook