HDDS-12136. Allow StorageVolumeChecker to be disabled

[Russole]

What changes were proposed in this pull request?

• Clarified validation for hdds.datanode.periodic.disk.check.interval.minutes:
  0 is treated as invalid and defaults to 60 to avoid accidental no-delay scheduling.
• Disabled the periodic disk checker when the configured interval is negative,
  and logged a warning to make the behavior explicit.
• Aligned the constant default value for the datanode periodic disk check
  interval with the @Config annotation default.
• Updated the invalid test input for the periodic disk check interval from -1
  to 0 to better represent an explicitly invalid configuration value.

What is the link to the Apache JIRA

https://issues.apache.org/jira/browse/HDDS-12136

How was this patch tested?

I relied on existing unit and integration tests, and verified that the full CI passed on my fork.
Please let me know if additional tests are needed.

[sreejasahithi]

Thanks @Russole for working on this.
Could you please add a test case to verify that negative values actually disable the periodic disk checker.

[sreejasahithi]

I think it would be good to update the @config description to document that negative values disable periodic disk checks and 0 is invalid (defaults to 60).

[Russole]

Thanks @sreejasahithi for the review. I’ve updated the commit and added the requested test.