Fix redis dependency

[DmitriGekhtman]

Why are these changes needed?

Something seems to have gone wrong in #26446.
Redis was not available in the built image.
This PR makes an attempt to fix the issue.

I'm not sure how to test this PR.
I will try to verify the PR manually by poking around the CI environment.

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 :(

[pcmoritz]

You should be able to build that docker image locally and see if this does the right thing (running the commend from the CI manually from your laptop)

[DmitriGekhtman]

You should be able to build that docker image locally and see if this does the right thing (running the commend from the CI manually from your laptop)

Thanks for the tip. Let me try it out -- it might not have worked out last time I tried it on a Mac.

[DmitriGekhtman]

Ok, I figured out how to work the build command locally. Now just need to fidget the formatting some more with some local experiments.

[DmitriGekhtman]

It seems I had some spare spaces.
I've opened a separate PR (not for merging) to verify https://github.com/ray-project/ray/pull/26480/files.

[DmitriGekhtman]

Verified that it works in https://buildkite.com/ray-project/ray-builders-pr/builds/37972#0181f40c-b88f-468e-ae1d-0716246005b4

[DmitriGekhtman]

Thank you for the stamps. Will pull nightly to re-confirm once it's built in ~1 hour.