Spike: Investigate using parallel GitHub actions to speed up PR builds

[LilyL0u]

Resolves JIRA: https://bbc.atlassian.net/browse/WS-55

Spike paper doc: https://paper.dropbox.com/doc/Spike-Investigate-using-parallel-GitHub-actions-to-speed-up-PR-builds--CzZ7YvmMmRwR4JvHRJN~SZVeAg-FV8xmJTgsQnCZgs9RPaNK

Now that we've integrated the Next.JS app into the Github action pipeline, we should look into what what can do with parallelisation to help speed up the PR build and test process:

It may also be worth looking into Jest sharding which makes use of GitHub matrices

Work to do: separate out these two commands into different workflows: PART 1 and PART 2

This pull request updates the GitHub Actions workflows for Cypress end-to-end (E2E) testing to improve parallelization and test sharding for both the Application and NextJS projects. It introduces a new workflow for the Application E2Es and refactors the NextJS workflow to match, enabling both to run E2E tests in parallel shards for faster feedback and more efficient CI usage.

Developer Checklist

• UX
  • UX Criteria met (visual UX & screenreader UX)
• Accessibility
  • Accessibility Acceptance Criteria met
  • Accessibility swarm completed
  • Component Health updated
  • P1 accessibility bugs resolved
  • P2/P3 accessibility bugs planned (if not resolved)
• Security
  • Security issues addressed
  • Threat Model updated
• Documentation
  • Docs updated (runbook, READMEs)
• Testing
  • Feature tested on relevant environments
• Comms
  • Relevant parties notified of changes

Testing

• Manual Testing required?
  • Local (Ready-For-Test, Local)
  • Test (Ready-For-Test, Test)
  • Preview (Ready-For-Test, Preview)
  • Live (Ready-For-Test, Live)
• Manual Testing complete?
  • Local
  • Test
  • Preview
  • Live

Additional Testing Steps

1. List the steps required to test this PR.

Useful Links

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[Isabella-Mitchell]

Thanks for doing this, your write up is really helpful and thorough.

It seems like something we could do since we're not at 20 cap yet. But perhaps we'd have to remove one day if another test takes precedent.

I also would be interested to know the timeline for full NextJS migration (if I'm right in thinking we could remove the 'Pages' test after this). Simply because if that's slow running, we may not see the benefit from sharding (though we will have failing faster).