[8.16] Adds LLM matrix for OSS models (backport #6424)

[mergify]

Fixes #6396 — adds a second matrix to the LLM performance matrix page that describes the performance of open-source models on our tasks. Also flips the existing matrix rows and columns so it can fit better in a browser window (minimize the need to scroll left-right).

Finally, makes a minor addition to the bring your own LLM guide, linking to the performance matrix since it now includes info about open source models.

Previews:

• LLM Performance matrix (ESS) (Serverless)
• BYO LLM setup guide (ESS) (Serverless)

  ---

  This is an automatic backport of pull request Adds LLM matrix for OSS models #6424 done by Mergify.

[mergify]

Cherry-pick of 6d64b54 has failed:

On branch mergify/bp/8.16/pr-6424
Your branch is up to date with 'origin/8.16'.

You are currently cherry-picking commit 6d64b54e.
  (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/AI-for-security/connect-to-byo.asciidoc
	modified:   docs/AI-for-security/llm-performance-matrix.asciidoc

Unmerged paths:
  (use "git add/rm <file>..." as appropriate to mark resolution)
	deleted by us:   docs/serverless/AI-for-security/connect-to-byo-llm.asciidoc
	deleted by us:   docs/serverless/AI-for-security/llm-performance-matrix.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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