Define and set up a 5k reference architecture configuration

Example customer requirements:

• Scale - 5k users
• 100 RPS

Acceptance criteria for certification (tentative):

• Latencies at 100 RPS on the 5k environment should be less than 500ms, with the exception of known bugs affecting certain endpoints.
• Endpoints that have known bugs have issues created and fed into the Performance Grooming process.
• Documentation has been added to describe the 5k environment's configuration.

Diagram

• Google Drawing TBD

Documentation

• TBD https://docs.gitlab.com/ee/administration/high_availability/