[Test][HA] RayService high-availability test without autoscaling enabled

[kevin85421]

Why are these changes needed?

See https://github.com/ray-project/kuberay/issues/2177 for more details.

Related issue number

Checks

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