Deployment updates

[microbit-matt-hillsdon]

Plan:

• [x] Check review branch deploy.
• [x] Update review CF and DNS.
  • Done, e.g. https://review-python-editor-v3.microbit.org/deployment/ works. See also notes below.
• [x] Remove redundant environment variables from CircleCI
• [x] Merge this PR (not much choice to check staging properly)
• [x] Check staging deploy
• [x] Update staging versioner beta
  • Done, now serving at https://stage-python.microbit.org/v/beta
  • More testing required tomorrow
• [x] Tag a pre-release
• [x] Check release deploy
• [x] Try /v/3/ on staging versioner
• [x] /v/beta on live versioner, replacing current beta
• [x] Use /v/beta in micro:bit classroom
  • Done but not released, one to discuss on Monday
• [x] Add notes to the clean-up task

All done except for the classroom release which is tracked elsewhere.

[github-actions[bot]]

Preview build will be at https://review-python-editor-next.microbit.org/deployment/

[microbit-matt-hillsdon]

Review deployments are working at https://review-python-editor-v3.microbit.org/deployment/

Remaining review actions:

• [x] The GH action that puts the link on PRs needs updating.
  • https://github.com/microbit-foundation/python-editor-v3/pull/988
• [ ] The old CNAME can be removed from the CF distribution
• [ ] The old review content has been copied over but needs its acl prodding to make it visible
• [ ] The old bucket can then be deleted

[microbit-matt-hillsdon]

The staging deployment isn't quite right. It's deployed to the correct path but with PUBLIC_URL unset. This is because it's only called for the review stage. Follow-up PR here: https://github.com/microbit-foundation/python-editor-v3/pull/987