Mocked GCE metadata to fix the Stackdriver local test failure

[0xaravindh]

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:

Fix Stackdriver metrics test by mocking GCE metadata server

Which issue(s) this PR fixes:

Closes #4212

Special notes for your reviewer:

[agones-bot]

Build Failed 😭

Build Id: 2f97232d-0403-4b6c-9155-aa4529a8fe81

Status: FAILURE

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[agones-bot]

Build Succeeded 🥳

Build Id: bd47cb7a-d980-4e6b-944f-d6166be50bab

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:1.51.0-dev-885d017
• image: us-docker.pkg.dev/agones-images/ci/agones-extensions:1.51.0-dev-885d017
• image: us-docker.pkg.dev/agones-images/ci/agones-sdk:1.51.0-dev-885d017-linux
• image: us-docker.pkg.dev/agones-images/ci/agones-ping:1.51.0-dev-885d017
• image: us-docker.pkg.dev/agones-images/ci/agones-allocator:1.51.0-dev-885d017
• Linux C++ SDK (build): agonessdk-1.51.0-dev-885d017-linux-arch_64.tar.gz
• SDK Server: agonessdk-server-1.51.0-dev-885d017.zip

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

• https://885d017-dot-preview-dot-agones-images.appspot.com/

To install this version:

git fetch https://github.com/googleforgames/agones.git pull/4215/head:pr_4215 && git checkout pr_4215
helm install agones ./install/helm/agones --namespace agones-system --set agones.image.registry=us-docker.pkg.dev/agones-images/ci --set agones.image.tag=1.51.0-dev-885d017

[markmandel]

I think this is the best options - the only other option I came up with was to have a Fatal handler on Logrus:
https://github.com/sirupsen/logrus?tab=readme-ov-file#fatal-handlers

But since we're testing for "NoPanic", probably better to mock the metadata service.

@igooch I'm approving, but checking if you any have any objections?

[agones-bot]

Build Succeeded 🥳

Build Id: f7ae95fc-346b-4f6f-abbd-ffa35cfbc813

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:1.51.0-dev-887a8c3
• image: us-docker.pkg.dev/agones-images/ci/agones-extensions:1.51.0-dev-887a8c3
• image: us-docker.pkg.dev/agones-images/ci/agones-sdk:1.51.0-dev-887a8c3-linux
• image: us-docker.pkg.dev/agones-images/ci/agones-ping:1.51.0-dev-887a8c3
• image: us-docker.pkg.dev/agones-images/ci/agones-allocator:1.51.0-dev-887a8c3
• Linux C++ SDK (build): agonessdk-1.51.0-dev-887a8c3-linux-arch_64.tar.gz
• SDK Server: agonessdk-server-1.51.0-dev-887a8c3.zip

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

• https://887a8c3-dot-preview-dot-agones-images.appspot.com/

To install this version:

git fetch https://github.com/googleforgames/agones.git pull/4215/head:pr_4215 && git checkout pr_4215
helm install agones ./install/helm/agones --namespace agones-system --set agones.image.registry=us-docker.pkg.dev/agones-images/ci --set agones.image.tag=1.51.0-dev-887a8c3