[Onboarding] Remove the system logs onboarding flow

[gbamparop]

:notebook: Summary

As system logs are now included in the new auto-detect flow for logs and metrics the dedicated system logs flow is no longer needed. Although the option has been removed from the Observability onboarding landing page, the page is still accessible by specifying the URL as the code lives in Kibana. This should be removed to make the codebase cleaner.

✔ Acceptance criteria

• All of the code that is related to the system logs onboarding flow should be deleted, including tests

Links

• https://github.com/elastic/kibana/issues/192624

[elasticmachine]

Pinging @elastic/obs-ux-onboarding-team (Feature: Observability Onboarding)

[elasticmachine]

Pinging @elastic/obs-ux-logs-team (Team:obs-ux-logs)