Refactor metrics registry exporter

[kamaljeeti]

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:

Which issue(s) this PR fixes:#3924

Closes #3924

Special notes for your reviewer:

[agones-bot]

Build Failed 😭

Build Id: 5a3988dc-b3c3-4208-83a3-26a07197f828

Status: FAILURE

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[agones-bot]

Build Failed 😭

Build Id: 8737d81b-cf40-47ab-9dc0-b65113007e9e

Status: FAILURE

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[agones-bot]

Build Succeeded 🥳

Build Id: 932f1635-1a2a-4485-93e3-af413b4dc77e

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:1.44.0-dev-af36937
• image: us-docker.pkg.dev/agones-images/ci/agones-extensions:1.44.0-dev-af36937
• image: us-docker.pkg.dev/agones-images/ci/agones-sdk:1.44.0-dev-af36937-linux
• image: us-docker.pkg.dev/agones-images/ci/agones-ping:1.44.0-dev-af36937
• image: us-docker.pkg.dev/agones-images/ci/agones-allocator:1.44.0-dev-af36937
• Linux C++ SDK (build): agonessdk-1.44.0-dev-af36937-linux-arch_64.tar.gz
• SDK Server: agonessdk-server-1.44.0-dev-af36937.zip

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

• https://af36937-dot-preview-dot-agones-images.appspot.com/

To install this version:

git fetch https://github.com/googleforgames/agones.git pull/3989/head:pr_3989 && git checkout pr_3989
helm install agones ./install/helm/agones --namespace agones-system --set agones.image.registry=us-docker.pkg.dev/agones-images/ci --set agones.image.tag=1.44.0-dev-af36937

[agones-bot]

Build Succeeded 🥳

Build Id: 0b1367b8-e48b-423f-b4d9-964949e39a44

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:1.44.0-dev-fd48eb1
• image: us-docker.pkg.dev/agones-images/ci/agones-extensions:1.44.0-dev-fd48eb1
• image: us-docker.pkg.dev/agones-images/ci/agones-sdk:1.44.0-dev-fd48eb1-linux
• image: us-docker.pkg.dev/agones-images/ci/agones-ping:1.44.0-dev-fd48eb1
• image: us-docker.pkg.dev/agones-images/ci/agones-allocator:1.44.0-dev-fd48eb1
• Linux C++ SDK (build): agonessdk-1.44.0-dev-fd48eb1-linux-arch_64.tar.gz
• SDK Server: agonessdk-server-1.44.0-dev-fd48eb1.zip

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

• https://fd48eb1-dot-preview-dot-agones-images.appspot.com/

To install this version:

git fetch https://github.com/googleforgames/agones.git pull/3989/head:pr_3989 && git checkout pr_3989
helm install agones ./install/helm/agones --namespace agones-system --set agones.image.registry=us-docker.pkg.dev/agones-images/ci --set agones.image.tag=1.44.0-dev-fd48eb1