[Test][RayCluster] Test redis cleanup job in the e2e compatibility test

[rueian]

Why are these changes needed?

As discussed with @kevin85421 offline, we think that we should test the redis cleanup job in the tests/compatibility-test.py.

This PR appends the cleanup_redis procedure to every test in the RayFTTestCase to test the cleanup job by deleting the RayCluster CR and watching the Redis' DBSIZE to zero. If it doesn't go zero before timeout, then the test will fail.

Related issue number

Fixes https://github.com/ray-project/kuberay/issues/1997

Checks

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

[kevin85421]

The CI stuck for 10 hours. I cancel it.

[rueian]

The CI stuck for 10 hours. I cancel it.

I will look into why did it stuck.