[App Search] Temporarily remove sidebar layout and internal engine links for 7.13 release

[cee-chen]

Summary

This PR hides our ongoing dev work on the final layout/engine pages until they're fully complete. (see #92228 for similar 7.12 PR)

QA

• Engines Overview takes the user to external App Search links, & doesnot inadvertantly take the user to the WIP Kibana plugin
• Setup Guide looks exactly the same as before

Checklist

• Unit or functional tests were updated or added to match the most common scenarios

[kibanamachine]

💚 Build Succeeded

• continuous-integration/kibana-ci/pull-request
• Commit: df9ad36
• Storybooks Preview

Metrics [docs]

Module Count

Fewer modules leads to a faster build time

id	before	after	diff
enterpriseSearch	1370	1367	-3

Async chunks

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

id	before	after	diff
enterpriseSearch	2.0MB	2.0MB	-5.3KB

History

• 💔 Build #122148 failed 85427b7262240969bbb0cc34ff9a31b568a5f5c7
• 💚 Build #122125 succeeded de97847448c285b9344229ed3470632c4f33d932

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@elasticmachine merge upstream