[k8s] Add cluster attributes(autodown, idle-minutes-to-autostop) as annotations to the pod

[landscapepainter]

This resolves #3869

Tested (run the relevant ones):

• Code formatting: bash format.sh
• Any manual or new tests for this PR (please specify below)
  • Test if annotations are added and remove as cancelling and reattaching autostop on kind/GKE:
  1. sky launch --cloud kubernetes -c mycluster -i 20 --down -y --num-nodes 3 --cpus=1: confirm if adds Annotations to the head/worker pods.
  2. sky autostop mycluster --cancel: confirm if removes the Annotations from the head/worker pods
  3. sky autostop mycluster -i 20 --down: confirm if adds back the Annotations to the head/worker pods.
  • Test sky launch with --down flag only without -i flag: confirm if Annotations for --down is added as True and Annotations for idle_minutes_to_autostop is added with value of 5 to the pod.
  • Test sky launch with -i flag only without --down flag: confirm if it fails to run as stopping is not supported for k8s.
• pytest tests/test_smoke.py --kubernetes -k "not TestStorageWithCredentials" except the ones that are failing on master branch as well:
  1. test_skyserve_fast_update
  2. test_managed_jobs_storage
• Relevant individual smoke tests: pytest tests/test_smoke.py::test_fill_in_the_name
• Backward compatibility tests: conda deactivate; bash -i tests/backward_compatibility_tests.sh

[landscapepainter]

@romilbhardwaj This is ready for another look!

[romilbhardwaj]

Thanks @landscapepainter!