Preparation for 1.18.0

[cindy52]

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:
Preparation for 1.18.0

Which issue(s) this PR fixes:

N/A

Special notes for your reviewer:

[agones-bot]

Build Failed 😱

Build Id: cabc1a4f-9737-4528-b0ca-0041f75011c8

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• Cloud Build log download

To get permission to view the Cloud Build view, join the agones-discuss Google Group.

[agones-bot]

Build Succeeded 👏

Build Id: 6762093b-7fbb-4755-820b-1b1fc1901ec2

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

• image: gcr.io/agones-images/agones-controller:1.18.0-c1ca052
• image: gcr.io/agones-images/agones-ping:1.18.0-c1ca052
• Linux C++ SDK (build): agonessdk-1.18.0-c1ca052-linux-arch_64.tar.gz
• SDK Server: agonessdk-server-1.18.0-c1ca052.zip

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

• https://c1ca052-dot-preview-dot-agones-images.appspot.com/

To install this version:

• git fetch https://github.com/googleforgames/agones.git pull/2250/head:pr_2250 && git checkout pr_2250
• helm install ./install/helm/agones --namespace agones-system --name agones --set agones.image.tag=1.18.0-c1ca052

[google-oss-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: cindy52, roberthbailey

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The pull request process is described here

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• OWNERS [roberthbailey]

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