[KubeRay] Pin autoscaler image

[DmitriGekhtman]

Why are these changes needed?

Sets the autoscaler image to the one from this PR's commit.
#22847

When Ray 1.12.0 is released, we will start using released versions of Ray for the autoscaler image.

Related issue number

Checks

• I've run scripts/format.sh to lint the changes in this PR.
• I've included any doc changes needed for https://docs.ray.io/en/master/.
• I've made sure the tests are passing. Note that there might be a few flaky tests, see the recent failures at https://flakey-tests.ray.io/
• Testing Strategy
  • Unit tests
  • Release tests
  • This PR is not tested :(

[DmitriGekhtman]

cc @Jeffwan , I'm going to follow up with the same change in the KubeRay repo.

[DmitriGekhtman]

cc @Jeffwan , I'm going to follow up with the same change in the KubeRay repo.

Actually, never mind!
I see the KubeRay repo has an independent image kuberay/autoscaler:nightly.
It's fine to manage that image independently.

We can discuss some more.

[Jeffwan]

Sounds good. For short term, we can use kuberay/autoscaler:nightly before v1.12.0 release. That might be easier