[8.14] 8.15.3 Release notes (backport #5905)

[mergify]

Fixes #5904 and updates the known issue summary for https://github.com/elastic/security-team/issues/10737 since it was fixed in 8.15.3.

Preview:

• 8.15.3 release notes - Added release notes for fixed bugs and known issues
• 8.15.x (8.15.0-8.15.2) - Updated known issue description for 5904.
• 8.14.x - Updated known issue description for 5904.

NOTE TO SELF: When the 8.14 backport PR is created, remember to remove the 8.15 release notes file.

---

This is an automatic backport of pull request #5905 done by Mergify.

[mergify]

Cherry-pick of 5ec4c64 has failed:

On branch mergify/bp/8.14/pr-5905
Your branch is up to date with 'origin/8.14'.

You are currently cherry-picking commit 5ec4c649.
  (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/release-notes/8.14.asciidoc

Unmerged paths:
  (use "git add/rm <file>..." as appropriate to mark resolution)
	both modified:   docs/release-notes.asciidoc
	deleted by us:   docs/release-notes/8.15.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

[github-actions]

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