[Enterprise Search][Search Applications] Remove overview page

[TattdCodeMonkey]

Summary

Removed the search applications overview page and replaced it as the default page with the search preview page.

[sphilipse]

Gotta delete some unused translation keys, but LGTM otherwise

[kibana-ci]

💛 Build succeeded, but was flaky

• Buildkite Build
• Commit: 5134cbf

Failed CI Steps

• FTR Configs #57

Metrics [docs]

Module Count

Fewer modules leads to a faster build time

id	before	after	diff
enterpriseSearch	2059	2057	-2

Async chunks

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

id	before	after	diff
enterpriseSearch	2.3MB	2.3MB	-3.5KB

Unknown metric groups

ESLint disabled line counts

id	before	after	diff
securitySolution	432	435	+3

Total ESLint disabled count

id	before	after	diff
securitySolution	512	515	+3

History

• 💔 Build #120491 failed 8b304c2b3d43532dc3b5bbe5495fdbfd191bc41e

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