[Doc] Switch K8S examples to default MP mode

[panpan0000]

PLEASE FILL IN THE PR DESCRIPTION HERE ENSURING ALL CHECKLIST ITEMS (AT THE BOTTOM) HAVE BEEN CONSIDERED.

Purpose

Fix #38113

per @ed-pai, previous k8s yaml won't work since default docker images has removed ray.
so switch the k8s yaml example to default mp(multiprocessing) as distributed backend.

Background:

• since v0.19.0 (per [RFC] Remove mandatory ray installation #33445), ray has been removed as default dependency as well as in docker image.
• which breaks lots of ray usage examples using k8s/docker.

This PR preserves the old ray code there as comments, in case some people still need it for reference or pip install ray by themselves.

Also add explicit --distributed-executor-backend ray for examples/online_serving/multi-node-serving.sh

Test Plan

apply the example LWS.md

Test Result

the actual vllm command as below , which aligns https://docs.vllm.ai/en/latest/serving/parallelism_scaling/#running-vllm-with-multiprocessing

cloudshell-worker-npvr4qhxq5:~# kubectl exec -it vllm-0 -- ps -lefww
....  /usr/bin/python3 /usr/local/bin/vllm serve meta-llama/Meta-Llama-3.1-405B-Instruct --tensor-parallel-size 8 --pipeline-parallel-size 2 --nnodes 2 --node-rank 0 --master-addr vllm-0.vllm.default --port 8080

cloudshell-worker-npvr4qhxq5:~# kubectl exec -it vllm-0-1 -- ps -lefww
....  /usr/bin/python3 /usr/local/bin/vllm serve meta-llama/Meta-Llama-3.1-405B-Instruct --tensor-parallel-size 8 --pipeline-parallel-size 2 --nnodes 2 --node-rank 1 --master-addr vllm-0.vllm.default --headless

---

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• The purpose of the PR, such as "Fix some issue (link existing issues this PR will resolve)".
• The test plan, such as providing test command.
• The test results, such as pasting the results comparison before and after, or e2e results
• (Optional) The necessary documentation update, such as updating supported_models.md and examples for a new model.
• (Optional) Release notes update. If your change is user facing, please update the release notes draft in the Google Doc.

BEFORE SUBMITTING, PLEASE READ https://docs.vllm.ai/en/latest/contributing (anything written below this line will be removed by GitHub Actions)

[mergify]

Documentation preview: https://vllm--39400.org.readthedocs.build/en/39400/

[gemini-code-assist]

Code Review

This pull request updates documentation and example configurations for distributed vLLM serving. It transitions from using a Ray-based multi-node serving script to direct vllm serve commands, explicitly configuring nodes, ranks, and master addresses, often leveraging the mp distributed executor backend. The changes include updating lws.md and kthena.md deployment examples, commenting out old Ray commands, and a minor typo fix. The review comments suggest improving consistency in argument formatting within the kthena.md documentation by using spaces instead of equals signs for parameters like --nnodes and --node-rank to enhance readability and reduce confusion.

[panpan0000]

@hmellor @yankay can you please take a look ?

[panpan0000]

comments addressed , thanks @hmellor

[hmellor]

Thanks this is looking better. The terminology used is inconsistent though. Please name the tabs Multiprocessing (default), Ray

[panpan0000]

Thanks this is looking better. The terminology used is inconsistent though. Please name the tabs Multiprocessing (default), Ray

all set . thanks @hmellor

[mergify]

This pull request has merge conflicts that must be resolved before it can be
merged. Please rebase the PR, @panpan0000.

https://docs.github.com/en/pull-requests/collaborating-with-pull-requests/working-with-forks/syncing-a-fork

[panpan0000]

This pull request has merge conflicts that must be resolved before it can be merged. Please rebase the PR, @panpan0000.

https://docs.github.com/en/pull-requests/collaborating-with-pull-requests/working-with-forks/syncing-a-fork

already addressed @mergify

[panpan0000]

all PR are rusted... Lol

[panpan0000]

Hi， @hmellor , PTAL again, thanks

[hmellor]

LGTM, just a few nits for consistency

[panpan0000]

THank you @hmellor