Breaching cypress best practices and tidying

[jamesbhobbs]

Is your feature request related to a problem? Please describe.
Cypress test in the repo are slightly untidy (subjective), breach many best practices (citations below) and will not scale (related in part to: #1837)

Describe the solution you'd like

• Folderise the tests e.g.
  -- pagetypeA, pagetypeB, utilities (wrongly in cypress/support), system, application etc.
• More consistent file naming (e.g. some start with amp, some end with it)
• e2es don't fast fail (meaning if 1 test fails early they tests will continue to run in their entirety)
• We should never ned to use let or const, we use them 145 times part of https://docs.cypress.io/guides/references/best-practices.html
• We have some tiny assertions breach of https://docs.cypress.io/guides/references/best-practices.html
• We have tests split by feature (not necessarily bad in principle) but this means we're loading and reloading each page we're running e2es on
• I think we're using config in /support where we should be using /fixtures
• Aside from duplication we have no way to run this same set of tests across multiple page types in 40 languages that we will need to
• Some code is written that duplicates native cypress functionality, such as testing for a 200 response
• Some of the e2e code is written to be as neat and reusable as production code, ironically this higher standard of code has made refactoring these tests harder than simply copying and pasting tests. There is little reason to avoid test duplication, we don't need to optimise the file sizes of tests, we need simpler, better structured tests that are easy for testers to CRUD (Create, Remove, Update, Delete).
• Tests should ideally be setup in a way that suits cypress parallelism as best as possible (it would work now, but would be inefficient)
• Some individual tests take 5-10s to run, this seems very long, perhaps there are errors here

Describe alternatives you've considered
n/a these tests need to be simple, clear and scalable

Testing notes
[Tester to complete]

Dev insight: This isn't just something that needs testing it's something that needs all testers to review as each change is made as they'll be the main users of these tests.

Additional context
Add any other context or screenshots about the feature request here.

[jamesbhobbs]

Part of #2230

[oluoluoxenfree]

Things left to do:

• test folderisation (if still wanted)
• I assume consistent file naming has been superceded by consolidating the tests
• e2es failing fast
• down to 62 instances of let/const but could still remove a few more
• duplication work arounds
• set up tests for parrellelism
• quicker running tests
• checking for native functionality duplication

[jamesbhobbs]

This is essentially done