HDDS-13402. Speed up TestOmSnapshotFileSystem

[adoroszlai]

What changes were proposed in this pull request?

Run TestOmSnapshotFileSystem* with a single cluster to reduce setup time.

https://issues.apache.org/jira/browse/HDDS-13402

How was this patch tested?

Before:

[INFO] Tests run: 8, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 44.06 s -- in org.apache.hadoop.ozone.om.snapshot.TestOmSnapshotFileSystemLegacy
[INFO] Tests run: 8, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 40.22 s -- in org.apache.hadoop.ozone.om.snapshot.TestOmSnapshotFileSystemFsoWithLinkedBuckets
[INFO] Tests run: 8, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 43.92 s -- in org.apache.hadoop.ozone.om.snapshot.TestOmSnapshotFileSystemLegacyWithLinkedBuckets
[INFO] Tests run: 8, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 40.47 s -- in org.apache.hadoop.ozone.om.snapshot.TestOmSnapshotFileSystemFso

After:

[INFO] Tests run: 8, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 22.89 s -- in org.apache.hadoop.ozone.om.snapshot.SnapshotTests$OmSnapshotFileSystemLegacyWithLinkedBuckets
[INFO] Tests run: 8, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 18.40 s -- in org.apache.hadoop.ozone.om.snapshot.SnapshotTests$OmSnapshotFileSystemLegacy
[INFO] Tests run: 8, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 15.18 s -- in org.apache.hadoop.ozone.om.snapshot.SnapshotTests$OmSnapshotFileSystemFsoWithLinkedBuckets
[INFO] Tests run: 8, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 14.30 s -- in org.apache.hadoop.ozone.om.snapshot.SnapshotTests$OmSnapshotFileSystemFso
[INFO] Tests run: 0, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 92.50 s -- in org.apache.hadoop.ozone.om.snapshot.TestOzoneSnapshotsNonHA

Total 92.5 seconds instead of 168.67.

https://github.com/adoroszlai/ozone/actions/runs/16119193466

[kerneltime]

org.apache.hadoop.hdds.scm.node.TestDecommissionAndMaintenance
Error:  org.apache.hadoop.hdds.scm.node.TestDecommissionAndMaintenance.testDecommissioningNodesCompleteDecommissionOnSCMRestart -- Time elapsed: 125.9 s <<< ERROR!
java.util.concurrent.TimeoutException: 
Timed out waiting for condition. Thread diagnostics:
Timestamp: 2025-07-07 03:53:43,872

[smengcl]

Thanks @adoroszlai ! Looks good code wise.

Was the timeout issue mentioned above related?

[adoroszlai]

Thanks @smengcl for the review.

Was the timeout issue mentioned above related?

No, I only changed test code and TestDecommissionAndMaintenance is a separate test (apparently still somewhat flaky).