[Guided onboarding] E2E testing plan

[alisonelizabeth]

In 8.6, we plan to deliver guided onboarding experiences across our solutions (prototype). Some of these experiences will involve navigating across different pages and apps in Kibana, and installing integrations.

These onboarding experiences are very UI dependent and we need to be able to catch if any future UI changes affect the E2E flow. This issue is to determine the best plan to be able to test these scenarios. I'd expect we would have an E2E test(s) per each guide.

Note: I'd also expect unit/component integration tests for the core UI component (tracked via #138557), but I would treat this as separate work.

[elasticmachine]

Pinging @elastic/platform-onboarding (Team:Journey/Onboarding)

[alisonelizabeth]

I'm going to close this for now. I think each solution/guide has been responsible for adding appropriate test coverage.