Legacy Ruby: Replace delete_completed_jobs script with Go

[sj-williams]

Background

We still use this Ruby script in Concourse Maintenance pipeline: https://github.com/ministryofjustice/cloud-platform-environments/blob/main/bin/delete_completed_jobs.rb

Pipeline: https://github.com/ministryofjustice/cloud-platform-terraform-concourse/blob/main/pipelines/manager/main/maintenance.yaml#L115

We should look at re-implementing the equivalent tool in Golang (standalone / CLI tool).

Proposed user journey

Approach

Which part of the user docs does this impact

Communicate changes

• [ ] post for #cloud-platform-update
• [ ] Weeknotes item
• [ ] Show the Thing/P&A All Hands/User CoP
• [ ] Announcements channel

Questions / Assumptions

Definition of done

• [ ] readme has been updated
• [ ] user docs have been updated
• [ ] another team member has reviewed
• [ ] smoke tests are green
• [ ] prepare demo for the team

Reference

How to write good user stories