Run ILM jest tests as integration tests allowing them to run beyond 5s timeout

[Dosant]

Summary

fix #141645
fix #141160
fix #115307

ILM heavy unit tests are flaky and can fail with a 5-second timeout. It happened in the past but it looks like it got worse with newly added features (#140804, #138748). (I assume that the problem is not specific to the new code, but just caused by adding more code)

We could have increased the timeout manually, but @spalger suggested to run these tests as integration tests. Here Spencer also explains the differences:

...the gist is that Jest integration tests are just in a different directory and have two main differences:

1. They never use parallelism, this allows them to access file system resources, launch services, etc. without needing to worry about conflicts with other tests
2. They are allowed to take their sweet time, the default timeout is currently 10 minutes.

Unit tests are really intended for testing one small piece of the code in isolation. Shared state between test/dependencies on previous tests, taking more than a few milliseconds to run, or integrating with many systems and running an entire simulated front-end application in Node are all examples of things that go beyond the scope of what a unit test is intended for.

In order to move these tests to be "integration tests" they should be in a directory named "integration_tests". These tests will run when you use node scripts/jest_integration <some_project_dir>.

[Dosant]

@elasticmachine merge upstream

[elasticmachine]

Pinging @elastic/platform-deployment-management (Team:Deployment Management)

[elasticmachine]

Pinging @elastic/kibana-app-services (Team:AppServicesUx)

[spalger]

👍 thank you @Dosant

[sebelga]

Awesome, thanks for doing this @Dosant !

[alisonelizabeth]

Changes LGTM. Thanks for addressing this @Dosant!

One small request 😄 What do you think about updating the README with some background information around these tests and why they were moved to integration_tests? The deployment management team owns many apps with similar testing infrastructure, and I could see someone coming back to the code confused why ILM follows a slightly different pattern.

[kibana-ci]

💚 Build Succeeded

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• Commit: e359df3

Metrics [docs]

✅ unchanged

History

• 💚 Build #76027 succeeded 144903b
• 💔 Build #75968 failed cfe3e0f
• 💚 Build #75559 succeeded 34ab6a0

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@elasticmachine merge upstream

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Status	Branch	Result
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