[ML] Transforms: Serverless functional tests for transform list.

[walterra]

Summary

Adds basic functional tests for serverless for the transform list. Since transforms are available in all project types, this adds the tests to common so they are run in all three project types.

• Navigates to the empty transform list and asserts the page.
• Checks transform is available as a search feature.

Checklist

• Unit or functional tests were updated or added to match the most common scenarios
• This was checked for breaking API changes and was labeled appropriately

[elasticmachine]

Pinging @elastic/ml-ui (:ml)

[pheyos]

LGTM with just one nit

[kibana-ci]

💚 Build Succeeded

• Buildkite Build
• Commit: 654f788

Metrics [docs]

✅ unchanged

History

• 💛 Build #170237 was flaky 7ccdec5

To update your PR or re-run it, just comment with:
@elasticmachine merge upstream

cc @walterra

[darnautov]

LGTM