Provision required VMs for DB benchmarking

Through terraform we need to create:

• 1 patroni node
• 2 pgbouncer nodes
• 2 jmeter nodes

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

Acceptance criteria

• Terraform MR that provisions the VMs is reviewed, merged and applied: https://ops.gitlab.net/gitlab-com/gitlab-com-infrastructure/-/merge_requests/2260