[8.x] Add TheHive connector for cases (backport #5859)

[mergify]

Relates to elastic/kibana#180931

This PR updates https://www.elastic.co/guide/en/security/current/cases-manage-settings.html#cases-ui-integrations and https://www.elastic.co/docs/current/serverless/security/cases-settings#external-incident-management-systems with support for TheHive connector in cases.

It also removes the table from the "Mapped case fields" section of those pages, since that reference information was outdated (e.g. missing the tags fields) and does not exist in the other solution-specific copies of this page. If that information is necessary, the most accurate source of truth seems to be the mapping.ts file in each connector folder under x-pack/plugins/cases/server/connectors.

Preview

• https://security-docs_bk_5859.docs-preview.app.elstc.co/guide/en/security/master/cases-manage-settings.html#cases-ui-integrations
• https://elastic-dot-co-docs-production-fz7jknxut-elastic-dev.vercel.app/current/serverless/security/cases-settings#external-incident-management-systems

  ---

  This is an automatic backport of pull request Add TheHive connector for cases #5859 done by Mergify.

[mergify]

Cherry-pick of 182b6f8 has failed:

On branch mergify/bp/8.x/pr-5859
Your branch is up to date with 'origin/8.x'.

You are currently cherry-picking commit 182b6f83.
  (fix conflicts and run "git cherry-pick --continue")
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  (use "git cherry-pick --abort" to cancel the cherry-pick operation)

Changes to be committed:
	modified:   docs/cases/cases-manage-settings.asciidoc

Unmerged paths:
  (use "git add/rm <file>..." as appropriate to mark resolution)
	deleted by us:   docs/serverless/investigate/cases-settings.mdx

To fix up this pull request, you can check it out locally. See documentation: https://docs.github.com/en/pull-requests/collaborating-with-pull-requests/reviewing-changes-in-pull-requests/checking-out-pull-requests-locally

[github-actions]

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