docs: Updated quickstart to use stable Istio release 1.28.0

[atharva-310]

What type of PR is this?
/kind documentation

What this PR does / why we need it:
This PR updates the quickstart guides to use the stable Istio release version 1.28.0, ensuring that users are running on a stable and fully supported version of Istio.

Which issue(s) this PR fixes:
Fixes #1856

Does this PR introduce a user-facing change?:

NONE

[netlify]

✅ Deploy Preview for gateway-api-inference-extension ready!

Name	Link
🔨 Latest commit	c1dd1f5
🔍 Latest deploy log	https://app.netlify.com/projects/gateway-api-inference-extension/deploys/692899a98e63a200082bf30c
😎 Deploy Preview	https://deploy-preview-1902--gateway-api-inference-extension.netlify.app
📱 Preview on mobile	Toggle QR Code... Use your smartphone camera to open QR code link.

---

To edit notification comments on pull requests, go to your Netlify project configuration.

[linux-foundation-easycla]

The committers listed above are authorized under a signed CLA.

• ✅ login: atharva-310 / name: Atharva Pakade (c1dd1f5)

[k8s-ci-robot]

Welcome @atharva-310!

It looks like this is your first PR to kubernetes-sigs/gateway-api-inference-extension 🎉. Please refer to our pull request process documentation to help your PR have a smooth ride to approval.

You will be prompted by a bot to use commands during the review process. Do not be afraid to follow the prompts! It is okay to experiment. Here is the bot commands documentation.

You can also check if kubernetes-sigs/gateway-api-inference-extension has its own contribution guidelines.

You may want to refer to our testing guide if you run into trouble with your tests not passing.

If you are having difficulty getting your pull request seen, please follow the recommended escalation practices. Also, for tips and tricks in the contribution process you may want to read the Kubernetes contributor cheat sheet. We want to make sure your contribution gets all the attention it needs!

Thank you, and welcome to Kubernetes. 😃

[k8s-ci-robot]

Hi @atharva-310. Thanks for your PR.

I'm waiting for a github.com member to verify that this patch is reasonable to test. If it is, they should reply with /ok-to-test on its own line. Until that is done, I will not automatically test new commits in this PR, but the usual testing commands by org members will still work. Regular contributors should join the org to skip this step.

Once the patch is verified, the new status will be reflected by the ok-to-test label.

I understand the commands that are listed here.

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the kubernetes-sigs/prow repository.

[nirrozenbaum]

/ok-to-test

[shmuelk]

@atharva-310 Your changes look great now. Please make sure that all of your commits are signed and verified

[nirrozenbaum]

/approve

leaving final stamp for @shmuelk

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: atharva-310, nirrozenbaum

The full list of commands accepted by this bot can be found here.

The pull request process is described here

Needs approval from an approver in each of these files:

• OWNERS [nirrozenbaum]

Approvers can indicate their approval by writing /approve in a comment
Approvers can cancel approval by writing /approve cancel in a comment