Move example images to Artifact Registry

[gongmax]

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

What this PR does / Why we need it:
We want eventually move all of the images generated to Artifact Registry. This PR move all the example images to the Artifact Registry us-docker.pkg.dev/agones-images/examples.

Which issue(s) this PR fixes:

Closes #2358

Special notes for your reviewer:
I have generated and pushed the following images to us-docker.pkg.dev/agones-images/examples:

allocation-endpoint
autoscaler-webhook
cpp-simple
nodejs-simple
rust-simple
unity-simple
xonotic
crd-client
supertuxkart
simple-game-server

[agones-bot]

Build Succeeded 👏

Build Id: 03a38bde-1f8c-4bea-a85e-2c609a2159af

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:1.28.0-c7db674-amd64
• image: us-docker.pkg.dev/agones-images/ci/agones-sdk:1.28.0-c7db674-linux-amd64
• image: us-docker.pkg.dev/agones-images/ci/agones-ping:1.28.0-c7db674-amd64
• image: us-docker.pkg.dev/agones-images/ci/agones-allocator:1.28.0-c7db674-amd64
• Linux C++ SDK (build): agonessdk-1.28.0-c7db674-amd64-linux-arch_64.tar.gz
• SDK Server: agonessdk-server-1.28.0-c7db674-amd64.zip

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

• https://c7db674-dot-preview-dot-agones-images.appspot.com/

To install this version:

• git fetch https://github.com/googleforgames/agones.git pull/2823/head:pr_2823 && git checkout pr_2823
• helm install agones ./install/helm/agones --namespace agones-system --set agones.image.tag=1.28.0-c7db674-amd64

[agones-bot]

Build Succeeded 👏

Build Id: 3eff5a03-4b9f-404f-ba83-d2323f434108

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:1.28.0-b599fda-amd64
• image: us-docker.pkg.dev/agones-images/ci/agones-sdk:1.28.0-b599fda-linux-amd64
• image: us-docker.pkg.dev/agones-images/ci/agones-ping:1.28.0-b599fda-amd64
• image: us-docker.pkg.dev/agones-images/ci/agones-allocator:1.28.0-b599fda-amd64
• Linux C++ SDK (build): agonessdk-1.28.0-b599fda-amd64-linux-arch_64.tar.gz
• SDK Server: agonessdk-server-1.28.0-b599fda-amd64.zip

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

• https://b599fda-dot-preview-dot-agones-images.appspot.com/

To install this version:

• git fetch https://github.com/googleforgames/agones.git pull/2823/head:pr_2823 && git checkout pr_2823
• helm install agones ./install/helm/agones --namespace agones-system --set agones.image.tag=1.28.0-b599fda-amd64

[markmandel]

LGTM!

[google-oss-prow]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: gongmax, markmandel, roberthbailey

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 [markmandel,roberthbailey]

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

[agones-bot]

Build Succeeded 👏

Build Id: e55b8c4a-bdd7-45f7-9339-32fdfe04c3dc

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:1.28.0-0b71c45-amd64
• image: us-docker.pkg.dev/agones-images/ci/agones-sdk:1.28.0-0b71c45-linux-amd64
• image: us-docker.pkg.dev/agones-images/ci/agones-ping:1.28.0-0b71c45-amd64
• image: us-docker.pkg.dev/agones-images/ci/agones-allocator:1.28.0-0b71c45-amd64
• Linux C++ SDK (build): agonessdk-1.28.0-0b71c45-amd64-linux-arch_64.tar.gz
• SDK Server: agonessdk-server-1.28.0-0b71c45-amd64.zip

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

• https://0b71c45-dot-preview-dot-agones-images.appspot.com/

To install this version:

• git fetch https://github.com/googleforgames/agones.git pull/2823/head:pr_2823 && git checkout pr_2823
• helm install agones ./install/helm/agones --namespace agones-system --set agones.image.tag=1.28.0-0b71c45-amd64

[agones-bot]

Build Succeeded 👏

Build Id: 91bb8f04-002f-457e-93b0-6f02ec321f70

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:1.28.0-20853e2-amd64
• image: us-docker.pkg.dev/agones-images/ci/agones-sdk:1.28.0-20853e2-linux-amd64
• image: us-docker.pkg.dev/agones-images/ci/agones-ping:1.28.0-20853e2-amd64
• image: us-docker.pkg.dev/agones-images/ci/agones-allocator:1.28.0-20853e2-amd64
• Linux C++ SDK (build): agonessdk-1.28.0-20853e2-amd64-linux-arch_64.tar.gz
• SDK Server: agonessdk-server-1.28.0-20853e2-amd64.zip

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

• https://20853e2-dot-preview-dot-agones-images.appspot.com/

To install this version:

• git fetch https://github.com/googleforgames/agones.git pull/2823/head:pr_2823 && git checkout pr_2823
• helm install agones ./install/helm/agones --namespace agones-system --set agones.image.tag=1.28.0-20853e2-amd64