Re-enable Gitaly transactions in staging after an incident

Gitaly transactions were disabled in incident 4141 to unblock a release. Re-enable them again when it is safe to do so.

• MR to be reverted: https://gitlab.com/gitlab-com/gl-infra/chef-repo/-/merge_requests/6436

This ticket was created from INC-4141 and was automatically exported by incident.io 🔥