Speed up CI unit-test workflow by 28%

[anshgoyalevil]

Which problem is this PR solving?

• I recently benchmarked against some jest settings to speed up the total test execution time.
• The best setting according to GitHub Actions so far, according to internet and manual testing is using --maxWorkers=4

How was this change tested?

• Executed in 5m 25 s with this setting: https://github.com/anshgoyalevil/jaeger-ui/actions/runs/6224545765/job/16892986157
• Executed in 8m without this setting: https://github.com/jaegertracing/jaeger-ui/actions/runs/6222381378/job/16886209310

Checklist

• I have read https://github.com/jaegertracing/jaeger/blob/master/CONTRIBUTING_GUIDELINES.md
• I have signed all commits
• I have added unit tests for the new functionality
• I have run lint and test steps successfully
  • for jaeger: make lint test
  • for jaeger-ui: yarn lint and yarn test

[codecov]

Codecov Report

Patch has no changes to coverable lines.

📢 Thoughts on this report? Let us know!.

[anshgoyalevil]

This PR got its test suite executed in 3m 29 seconds 🪐

[yurishkuro]

WOW!

[yurishkuro]

Q: when running test locally we use yarn test, which is different from test-ci. Is there also a possibility to increase its performance?

[anshgoyalevil]

Yes. There is, but it is yet to be tested manually. Some posts suggest having --maxWorkers=50% as the setting for local test scripts.
Would try this out with multiple options to find out the best combination.