Enable Advanced Search by Default for GitLab EE

Some of GitLab competitors offer a Search Integration that included Faceting and Filtering by default. We should consider how we could enable Elasticsearch by Default. Mentioned from #1711 (closed)

Impacts this would have

• All EE customers would likely use it. Currently, we only know of about 1K customers with it enabled.
• Decreases the need for some of our customers to use 3rd party solutions for searching across GitLab.
• We would make the Global Search product less confusing. We would have Core Search and EE Search. There would not be a combination of EE Basic search.

What would it take to enable Advanced Search by default?

• We would need to make sure customers are ok with the storage increase needed to operate the ES index.
• We would need to figure out the migration plan for Core users to EE.
• We would need a turnkey upgrade from GitLab 11.6 and after to the version which Elasticsearch became part of the EE package.
• We would need to solve for the need to have Elasticsearch on a different cluster.
• we would need to understand the performance impacts to GitLab running on the same cluster.

Next Incrmental Steps?

-Should we consider making ES a container install and adding to Omnibus?