feat: Implement BackendUtilization LB OutOfBand reporting

[jukie]

What this PR does / why we need it:

Implementation for #9400 plus docs and e2e

Which issue(s) this PR fixes:

Fixes #9401

[netlify]

✅ Deploy Preview for cerulean-figolla-1f9435 ready!

Name	Link
🔨 Latest commit	046e8d1
🔍 Latest deploy log	https://app.netlify.com/projects/cerulean-figolla-1f9435/deploys/6a6ae05cffa2c8000847b15a
😎 Deploy Preview	https://deploy-preview-9593--cerulean-figolla-1f9435.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.

[jukie]

Bump was needed to include the OrcaOobReportingConfig API field

[jukie]

@codex review

[chatgpt-codex-connector]

Codex Review: Didn't find any major issues. More of your lovely PRs please.

Reviewed commit: d90b0c865d

ℹ️ About Codex in GitHub

Your team has set up Codex to review pull requests in this repo. Reviews are triggered when you

• Open a pull request for review
• Mark a draft as ready
• Comment "@codex review".

If Codex has suggestions, it will comment; otherwise it will react with 👍.

Codex can also answer questions or update the PR. Try commenting "@codex address that feedback".

[codecov]

Codecov Report

❌ Patch coverage is 90.47619% with 2 lines in your changes missing coverage. Please review.
✅ Project coverage is 75.68%. Comparing base (f63003f) to head (637a0f6).

Files with missing lines	Patch %	Lines
internal/gatewayapi/clustersettings.go	80.00%	1 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #9593      +/-   ##
==========================================
- Coverage   75.70%   75.68%   -0.03%     
==========================================
  Files         254      254              
  Lines       42110    42131      +21     
==========================================
+ Hits        31880    31885       +5     
- Misses       8085     8096      +11     
- Partials     2145     2150       +5     

☔ View full report in Codecov by Harness.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.
• 📦 JS Bundle Analysis: Save yourself from yourself by tracking and limiting bundle sizes in JS merges.

[jukie]

CC @zhaohuabing #9400 (comment)

@zhaohuabing I ended up reverting this back to *int32. We only use it in one other place currently vs int32 for 8 other port fields and it breaks the kubebuilder bounds setup.

Let's continue here on whether to use PortNumber instead.