load test client make concurrent requests

[peterzhongyi]

The load test started clients concurrently, but didn't make request concurrently. Without this change, clients make synchronous allocation calls, which is super slow.

With this change, we can achieve allocation speed of ~300 GameServer per second. (Note that with 15 clients making 100 requests, the allocation speed was ~400 gameservers per second)

[agones-bot]

Build Succeeded 🥳

Build Id: b5fea322-6bd6-42dd-9edf-b7b55ce0ff03

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:1.49.0-dev-4770868
• image: us-docker.pkg.dev/agones-images/ci/agones-extensions:1.49.0-dev-4770868
• image: us-docker.pkg.dev/agones-images/ci/agones-sdk:1.49.0-dev-4770868-linux
• image: us-docker.pkg.dev/agones-images/ci/agones-ping:1.49.0-dev-4770868
• image: us-docker.pkg.dev/agones-images/ci/agones-allocator:1.49.0-dev-4770868
• Linux C++ SDK (build): agonessdk-1.49.0-dev-4770868-linux-arch_64.tar.gz
• SDK Server: agonessdk-server-1.49.0-dev-4770868.zip

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

• https://4770868-dot-preview-dot-agones-images.appspot.com/

To install this version:

git fetch https://github.com/googleforgames/agones.git pull/4149/head:pr_4149 && git checkout pr_4149
helm install agones ./install/helm/agones --namespace agones-system --set agones.image.registry=us-docker.pkg.dev/agones-images/ci --set agones.image.tag=1.49.0-dev-4770868

[igooch]

LGTM good catch.

[agones-bot]

Build Succeeded 🥳

Build Id: 74e2a610-9fa2-4be9-9cfc-e3d80c8191de

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:1.49.0-dev-70805d5
• image: us-docker.pkg.dev/agones-images/ci/agones-extensions:1.49.0-dev-70805d5
• image: us-docker.pkg.dev/agones-images/ci/agones-sdk:1.49.0-dev-70805d5-linux
• image: us-docker.pkg.dev/agones-images/ci/agones-ping:1.49.0-dev-70805d5
• image: us-docker.pkg.dev/agones-images/ci/agones-allocator:1.49.0-dev-70805d5
• Linux C++ SDK (build): agonessdk-1.49.0-dev-70805d5-linux-arch_64.tar.gz
• SDK Server: agonessdk-server-1.49.0-dev-70805d5.zip

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

• https://70805d5-dot-preview-dot-agones-images.appspot.com/

To install this version:

git fetch https://github.com/googleforgames/agones.git pull/4149/head:pr_4149 && git checkout pr_4149
helm install agones ./install/helm/agones --namespace agones-system --set agones.image.registry=us-docker.pkg.dev/agones-images/ci --set agones.image.tag=1.49.0-dev-70805d5