chore: promote PortPolicyNone feature gate from beta to stable

[mckean023]

What type of PR is this?

Uncomment only one /kind <> line, press enter to put that in a new line, and remove leading whitespace from that line:

/kind breaking
/kind bug

/kind cleanup

/kind documentation
/kind feature
/kind hotfix
/kind release

What this PR does / Why we need it:
Promotes PortPolicyNone from Beta to Stable. The feature gate is now enabled by default and all relevant references have been updated.

Which issue(s) this PR fixes:
Closes #4587

Did you use AI tools in preparing this PR?:
N

Special notes for your reviewer:

[mckean023]

Hey @markmandel, this would be my first contribution to Agones. My local build already completed so would you be able to /gcbrun since I cannot? Cheers.

[markmandel]

Appreciate the contribution, but this is a duplicate of the work being done at #4602

Happy to keep this PR in case that one falls through, but generally speaking - refrain from creating duplicate work PRs.

[markmandel]

Unfortunately the original PR has fallen through. if you want to pick this back up - please feel free.

[mckean023]

@markmandel Sounds good. Just looked over and updated a couple things as 1.59.0 released since I last worked on this. It should be good to /gcbrun.

[markmandel]

/gcbrun

[agones-bot]

Build Succeeded 🥳

Build Id: 7710fbb3-3f3a-4346-b32e-db4365196359

The following development artifacts have been built, and will exist for the next 30 days:

• image: us-docker.pkg.dev/agones-images/ci/agones-controller:1.60.0-dev-49c676d
• image: us-docker.pkg.dev/agones-images/ci/agones-extensions:1.60.0-dev-49c676d
• image: us-docker.pkg.dev/agones-images/ci/agones-sdk:1.60.0-dev-49c676d-linux
• image: us-docker.pkg.dev/agones-images/ci/agones-ping:1.60.0-dev-49c676d
• image: us-docker.pkg.dev/agones-images/ci/agones-allocator:1.60.0-dev-49c676d
• image: us-docker.pkg.dev/agones-images/ci/agones-processor:1.60.0-dev-49c676d
• Linux C++ SDK (build): agonessdk-1.60.0-dev-49c676d-linux-arch_64.tar.gz
• SDK Server: agonessdk-server-1.60.0-dev-49c676d.zip

A preview of the website (the last 30 builds are retained):

• https://49c676d-dot-preview-dot-agones-images.appspot.com/

To install this version:

git fetch https://github.com/googleforgames/agones.git pull/4627/head:pr_4627 && git checkout pr_4627
helm install agones ./install/helm/agones --namespace agones-system --set agones.image.registry=us-docker.pkg.dev/agones-images/ci --set agones.image.tag=1.60.0-dev-49c676d

[mckean023]

@markmandel OK the build was successful but it looked like I forgot to amend one of the older commits from before the 1.59.0 release for the docs on the website. I fixed that and just a couple other things I noticed. Should be good to /gcbrun again and then review if its successful.