ci: reorganise workflows [EXPERIMENTAL]

[0x009922]

Context

This is built on top of #5124 as an experiment to see if our CI could look more organised. I am confused each time looking at different workflows and their jobs and determining what is what.

Partially closes #4516

Solution

Remove old workflows; combine some; simpler names.

Migration Guide (optional)

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Review notes (optional)

Checklist

• [x] I've read CONTRIBUTING.md.
• [ ] (optional) I've written unit tests for the code changes.
• [ ] All review comments have been resolved.
• [ ] All CI checks pass.

[0x009922]

What is the difference between publish_what.yml and publish_what2.yml?