[8.15] [BUG] All Kibana privileges don't grant Security / Elastic Defend features by default (backport #6134)

[mergify]

Resolves #5785 by adding an admonition for emphasis.

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• Elastic Defend feature privileges (ESS) (serverless)

  ---

  This is an automatic backport of pull request [BUG] All Kibana privileges don't grant Security / Elastic Defend features by default #6134 done by Mergify.

[mergify]

Cherry-pick of 122bea2 has failed:

On branch mergify/bp/8.15/pr-6134
Your branch is up to date with 'origin/8.15'.

You are currently cherry-picking commit 122bea23.
  (fix conflicts and run "git cherry-pick --continue")
  (use "git cherry-pick --skip" to skip this patch)
  (use "git cherry-pick --abort" to cancel the cherry-pick operation)

Changes to be committed:
	modified:   docs/getting-started/defend-feature-privs.asciidoc

Unmerged paths:
  (use "git add/rm <file>..." as appropriate to mark resolution)
	deleted by us:   docs/serverless/edr-install-config/defend-feature-privs.asciidoc

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

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