[Inference UI] Add scout tests for feature settings page

[saikatsarkar056]

Summary

Adds Scout tests for the Feature Settings (Model Settings) page under Stack Management. This page allows users to configure default AI models and manage per-feature inference endpoint assignments.

How to run the tests

node scripts/scout.js start-server --arch stateful --domain classic
npx playwright test --config .../test/scout/ui/playwright.config.ts --project local --headed feature_settings.spec

Checklist

Check the PR satisfies following conditions.

Reviewers should verify this PR satisfies this list as well.

• Any text added follows EUI's writing guidelines, uses sentence case text and includes i18n support
• Documentation was added for features that require explanation or tutorials
• Unit or functional tests were updated or added to match the most common scenarios
• If a plugin configuration key changed, check if it needs to be allowlisted in the cloud and added to the docker list
• This was checked for breaking HTTP API changes, and any breaking changes have been approved by the breaking-change committee. The release_note:breaking label should be applied in these situations.
• Flaky Test Runner was used on any tests changed
• The PR description includes the appropriate Release Notes section, and the correct release_note:* label is applied per the guidelines
• Review the backport guidelines and apply applicable backport:* labels.

Identify risks

Does this PR introduce any risks? For example, consider risks like hard to test bugs, performance regression, potential of data loss.

Describe the risk, its severity, and mitigation for each identified risk. Invite stakeholders and evaluate how to proceed before merging.

• See some risk examples
• ...

[macroscopeapp]

Approvability

Verdict: Needs human review

CODEOWNERS file was modified by a non-owner — requires human review

^{You can customize Macroscope's approvability policy. Learn more.}

[kibanamachine]

Flaky Test Runner Stats

🎉 All tests passed! - kibana-flaky-test-suite-runner#11437

[✅] x-pack/platform/plugins/shared/search_inference_endpoints/test/scout/ui/playwright.config.ts: 15/15 tests passed.

see run history

[kibanamachine]

Flaky Test Runner Stats

🟠 Some tests failed. - kibana-flaky-test-suite-runner#11530

[❌] x-pack/platform/plugins/shared/search_inference_endpoints/test/scout_inference_test/ui/playwright.config.ts: 14/15 tests passed.

see run history

[kibanamachine]

Flaky Test Runner Stats

🎉 All tests passed! - kibana-flaky-test-suite-runner#11534

[✅] x-pack/platform/plugins/shared/search_inference_endpoints/test/scout_inference_test/ui/playwright.config.ts: 20/20 tests passed.

see run history

[csr]

Overall LGTM, I've added a few suggestions. Feel free to re-request my review anytime.

[elasticmachine]

💛 Build succeeded, but was flaky

• Buildkite Build
• Commit: 7a70e17

Failed CI Steps

• FTR Configs #210

Test Failures

• [job] [logs] FTR Configs #210 / console app console autocomplete feature ESQL queries does not suggest ESQL when inside non-query triple quotes

Metrics [docs]

Async chunks

Total size of all lazy-loaded chunks that will be downloaded as the user navigates the app

id	before	after	diff
searchInferenceEndpoints	216.2KB	216.2KB	+40.0B

History

• 💚 Build #425865 succeeded 7deba2d
• 💔 Build #425781 failed 798d229
• 💔 Build #425208 failed 56748f1

cc @saikatsarkar056