[Functional tests] Drop legacyEs usage

[afharo]

Summary

Apparently, #88720 and #80945 happened concurrently and one more usage of legacyEs was introduced.

This PR replaces the use of the service legacyEs in favour of the new es.

Checklist

Delete any items that are not applicable to this PR.

• 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
• Any UI touched in this PR is usable by keyboard only (learn more about keyboard accessibility)
• Any UI touched in this PR does not create any new axe failures (run axe in browser: FF, Chrome)
• If a plugin configuration key changed, check if it needs to be whitelisted in the cloud and added to the docker list
• This renders correctly on smaller devices using a responsive layout. (You can test this in your browser)
• This was checked for cross-browser compatibility

For maintainers

• This was checked for breaking API changes and was labeled appropriately

[afharo]

@elasticmachine merge upstream

[kibanamachine]

💚 Build Succeeded

• continuous-integration/kibana-ci/pull-request
• Commit: 28943c5

Metrics [docs]

✅ unchanged

History

• 💔 Build #100262 failed f09202c

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

[afharo]

Can't backport until #88917 is merged

[kibanamachine]

Friendly reminder: Looks like this PR hasn’t been backported yet.
To create backports run node scripts/backport --pr 88939 or prevent reminders by adding the backport:skip label.