Removal of getRandomlySelectedGS

[markmandel]

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:

When refactoring the allocator code for #2143 I noticed that this function was never actually utilised for anything, so figured it made
sense to remove it.

Which issue(s) this PR fixes:

N/A

Special notes for your reviewer:

N/A

[agones-bot]

Build Succeeded 👏

Build Id: ef50f885-3b85-45d5-8c11-7844fff74ecf

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

• image: gcr.io/agones-images/agones-controller:1.16.0-bfed18c
• image: gcr.io/agones-images/agones-ping:1.16.0-bfed18c
• Linux C++ SDK (build): agonessdk-1.16.0-bfed18c-linux-arch_64.tar.gz
• SDK Server: agonessdk-server-1.16.0-bfed18c.zip

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

• https://bfed18c-dot-preview-dot-agones-images.appspot.com/

To install this version:

• git fetch https://github.com/googleforgames/agones.git pull/2144/head:pr_2144 && git checkout pr_2144
• helm install ./install/helm/agones --namespace agones-system --name agones --set agones.image.tag=1.16.0-bfed18c

[google-oss-robot]

[APPROVALNOTIFIER] This PR is APPROVED

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

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• OWNERS [markmandel,roberthbailey]

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