Create required chef-repo roles for DB benchmarking

As a prerequisite for creating the patroni, pgbouncer and jmeter nodes requried for the new db-benchmarking environment, we need the chef-roles that will provision them.

Part of https://gitlab.com/gitlab-com/gl-infra/infrastructure/-/issues/12113

Acceptance criteria

chef-repo MR that creates the environment and roles is merged and applied: https://ops.gitlab.net/gitlab-cookbooks/chef-repo/-/merge_requests/4793

Edited Dec 23, 2020 by Alejandro Rodríguez