featuregate: adds validation if PortPolicyNone is not enabled

[daniellee]

When the feature gate PortPolicyNone is used, validation should fail if the PortPolicy field is set to the value None.

What type of PR is this?
/kind bug

What this PR does / Why we need it:
Without this validation, then the Container Port is set to 0 and it silently fails.

Which issue(s) this PR fixes:
Closes #3867

Special notes for your reviewer:

[agones-bot]

Build Succeeded 👏

Build Id: c976d4fc-f218-467c-8b07-42c77f6d5d0d

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:1.42.0-dev-9c9ccac-amd64
• image: us-docker.pkg.dev/agones-images/ci/agones-extensions:1.42.0-dev-9c9ccac-amd64
• image: us-docker.pkg.dev/agones-images/ci/agones-sdk:1.42.0-dev-9c9ccac-linux-amd64
• image: us-docker.pkg.dev/agones-images/ci/agones-ping:1.42.0-dev-9c9ccac-amd64
• image: us-docker.pkg.dev/agones-images/ci/agones-allocator:1.42.0-dev-9c9ccac-amd64
• Linux C++ SDK (build): agonessdk-1.42.0-dev-9c9ccac-amd64-linux-arch_64.tar.gz
• SDK Server: agonessdk-server-1.42.0-dev-9c9ccac-amd64.zip

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

• https://9c9ccac-dot-preview-dot-agones-images.appspot.com/

To install this version:

• git fetch https://github.com/googleforgames/agones.git pull/3871/head:pr_3871 && git checkout pr_3871
• helm install agones ./install/helm/agones --namespace agones-system --set agones.image.registry=us-docker.pkg.dev/agones-images/ci --set agones.image.tag=1.42.0-dev-9c9ccac-amd64

[igooch]

LGTM

[agones-bot]

Build Succeeded 👏

Build Id: 519b0e81-0522-48b0-82d4-20d0fb511646

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:1.42.0-dev-26d392a-amd64
• image: us-docker.pkg.dev/agones-images/ci/agones-extensions:1.42.0-dev-26d392a-amd64
• image: us-docker.pkg.dev/agones-images/ci/agones-sdk:1.42.0-dev-26d392a-linux-amd64
• image: us-docker.pkg.dev/agones-images/ci/agones-ping:1.42.0-dev-26d392a-amd64
• image: us-docker.pkg.dev/agones-images/ci/agones-allocator:1.42.0-dev-26d392a-amd64
• Linux C++ SDK (build): agonessdk-1.42.0-dev-26d392a-amd64-linux-arch_64.tar.gz
• SDK Server: agonessdk-server-1.42.0-dev-26d392a-amd64.zip

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

• https://26d392a-dot-preview-dot-agones-images.appspot.com/

To install this version:

• git fetch https://github.com/googleforgames/agones.git pull/3871/head:pr_3871 && git checkout pr_3871
• helm install agones ./install/helm/agones --namespace agones-system --set agones.image.registry=us-docker.pkg.dev/agones-images/ci --set agones.image.tag=1.42.0-dev-26d392a-amd64