chore(834): cypress upgrade

[JohnTParsons]

closes #834

What

I tried prepending the cypress scripts in package.json with "ELECTRON_EXTRA_LAUNCH_ARGS=--disable-gpu" but made no difference.

So have just upgraded to latest Cypress version
and reduced the docs runners from 6 to 4 (same as comps, which has been stable).

I have done:

• Written unit tests against changes
• Written functional tests against the component and/or NewsKit site
• Updated relevant documentation

I have tested manually:

• The feature's functionality is working as expected on Chrome, Firefox, Safari and Edge
• The screen reader reads and flows through the elements as expected.
• There are no new errors in the browser console coming from this PR.
• When visual test is not added, it renders correctly on different browsers and mobile viewports (Safari, Firefox, small mobile viewport, tablet)
• The Playground feature is working as expected

Before:

After:

Who should review this PR:

How to test:

[pp-serviceaccount]

You can preview these changes on:
Documentation Site: http://ncu-newskit-docs-pr.s3-website-eu-west-1.amazonaws.com/834-cypress-failures
Storybook: http://ncu-newskit-docs-pr.s3-website-eu-west-1.amazonaws.com/834-cypress-failures/storybook

[JohnTParsons]

I moved the simple change to reduce parallel runners from 6 to 4 into a different PR yesterday as the Cypress upgrade in this branch was getting test failures (though that might just have been an intermittent issue as has started working again today). Inclined to merge this PR after the next release to be on the safe side.

[jps]

@JohnTParsons I had a go at the other approach mentioned in this blog post

I'm inclined to most forward with it as feel it's more flexible and stable that the cypress-parallel library

Here is what the results look like in circle