Add steps to update performance test clusters when upgrading k8s version

[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
/kind release

What this PR does / Why we need it:
We introduced a performance test cluster recently. It's version needs to be updated when we update the supported k8s version. Add steps for the purpose.

Which issue(s) this PR fixes:

Closes #

Special notes for your reviewer:

[agones-bot]

Build Succeeded 👏

Build Id: b983d850-4d79-4414-8c87-9464c9978b92

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:1.37.0-dev-ed422c0-amd64
• image: us-docker.pkg.dev/agones-images/ci/agones-extensions:1.37.0-dev-ed422c0-amd64
• image: us-docker.pkg.dev/agones-images/ci/agones-sdk:1.37.0-dev-ed422c0-linux-amd64
• image: us-docker.pkg.dev/agones-images/ci/agones-ping:1.37.0-dev-ed422c0-amd64
• image: us-docker.pkg.dev/agones-images/ci/agones-allocator:1.37.0-dev-ed422c0-amd64
• Linux C++ SDK (build): agonessdk-1.37.0-dev-ed422c0-amd64-linux-arch_64.tar.gz
• SDK Server: agonessdk-server-1.37.0-dev-ed422c0-amd64.zip

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

• https://ed422c0-dot-preview-dot-agones-images.appspot.com/

To install this version:

• git fetch https://github.com/googleforgames/agones.git pull/3501/head:pr_3501 && git checkout pr_3501
• helm install agones ./install/helm/agones --namespace agones-system --set agones.image.registry=us-docker.pkg.dev/agones-images/ci --set agones.image.tag=1.37.0-dev-ed422c0-amd64

[Kalaiselvi84]

LGTM!

[google-oss-prow]

New changes are detected. LGTM label has been removed.

[google-oss-prow]

[APPROVALNOTIFIER] This PR is APPROVED

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

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• OWNERS [markmandel]

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[agones-bot]

Build Succeeded 👏

Build Id: 0f716589-ab5e-4f8b-bdfc-c4551555a95a

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:1.37.0-dev-702edc8-amd64
• image: us-docker.pkg.dev/agones-images/ci/agones-extensions:1.37.0-dev-702edc8-amd64
• image: us-docker.pkg.dev/agones-images/ci/agones-sdk:1.37.0-dev-702edc8-linux-amd64
• image: us-docker.pkg.dev/agones-images/ci/agones-ping:1.37.0-dev-702edc8-amd64
• image: us-docker.pkg.dev/agones-images/ci/agones-allocator:1.37.0-dev-702edc8-amd64
• Linux C++ SDK (build): agonessdk-1.37.0-dev-702edc8-amd64-linux-arch_64.tar.gz
• SDK Server: agonessdk-server-1.37.0-dev-702edc8-amd64.zip

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

• https://702edc8-dot-preview-dot-agones-images.appspot.com/

To install this version:

• git fetch https://github.com/googleforgames/agones.git pull/3501/head:pr_3501 && git checkout pr_3501
• helm install agones ./install/helm/agones --namespace agones-system --set agones.image.registry=us-docker.pkg.dev/agones-images/ci --set agones.image.tag=1.37.0-dev-702edc8-amd64