Convert mean-time-to-repair.rb to go

[mikebell]

Background

Source files - https://github.com/ministryofjustice/cloud-platform/tree/main/runbooks/bin

Convert this from ruby to go. Also move it from /runbooks/bin to /cmd/mean-time-to-repaire

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

[mikebell]

PR: #6250