Release 2744

Trello card

https://trello.com/c/SPbIS1pl

Context

Reducing GitHub secrets reduces management overhead and makes this workflow easier to generalise.

Changes proposed in this pull request

• Get KeyVault name for sp_check from matrix data instead of a GitHub secret.
• Pinned major version of rtCamp/action-slack-notify

Guidance to review

Checks logs on test run.