[test](schema-change) log alter job state in test_schema_change_mow_with_empty_rowset

[shuke987]

Proposed changes

Add a logger.info to print the alter table job state that is polled inside the Awaitility loop in test_schema_change_mow_with_empty_rowset.groovy.

The test waits for the schema-change job to reach FINISHED/CANCELLED but does not log the intermediate state. When the job stalls or ends up CANCELLED, the regression log shows no trace of the observed state, making failures hard to diagnose. Logging the polled res each iteration makes such failures self-explanatory from the test output.

No behavior change to the test logic itself.

Checklist

• No new test needed (logging-only change to an existing regression test)
  🤖 Generated with Claude Code

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