[autoscaler] Add env RAY_ENABLE_CLUSTER_STATUS_LOG to disable periodic cluster status log.

[DmitriGekhtman]

Why are these changes needed?

This PR adds an env flag to disable periodic autoscaler cluster status logging.

Users may wish to disable these logs because:

• The log entry is rather long and communicates cluster status rather than events in the cluster.
• The log is multi-line, which does not interact well with some users' logging setups.
• You can get the same info by running ray status.

Related issue number

#26670

Checks

• I've signed off every commit(by using the -s flag, i.e., git commit -s) in this PR.
• 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 :(

[wuisawesome]

lgtm

[DmitriGekhtman]

test_basic is known to be flakey

[mbbyn]

I believe RAY_ENABLE_CLUSTER_STATUS_LOG is completely missing from the docs