add initial perf tests for 100 RayCluster and 100 RayJob

[andrewsykim]

Why are these changes needed?

This PR introduces two initial (small scale) performance tests for KubeRay testing 100 RayClusters and 100 RayJobs. The scalability tests use clusterloader2, a Kubernetes load testing tool maintained by the Kubernetes project.

Related issue number

https://github.com/ray-project/kuberay/issues/2069

Checks

• [ ] I've made sure the tests are passing.
• Testing Strategy
  • [ ] Unit tests
  • [ ] Manual tests
  • [ ] This PR is not tested :(