HDDS-14629. Code cleanup after HDDS-13906

[Russole]

What changes were proposed in this pull request?

• Refactor OMDBArchiver to own and initialize the hardlink mapping internally, removing setHardLinkFileMap() and nullable state.
• Normalize and convert paths to absolute form before calling relativize() in writeHardlinkFile to prevent abs/relative path mismatch exceptions.
• Stop exposing internal hardlink map and use recordHardLinkMapping() instead.
• Return HTTP 500 when archive streaming fails to ensure proper error handling.

What is the link to the Apache JIRA

https://issues.apache.org/jira/browse/HDDS-14629

How was this patch tested?

• All tests passed except those currently pending fixes
  • https://github.com/Russole/ozone/actions/runs/22050572851

[yandrey321]

can this one be null or empty?

[Russole]

dbFile comes from either Files.list(...) or from a List<Path> created in extractSSTFilesFromCompactionLog().

From directory listing:

try (Stream<Path> files = Files.list(dbDir)) {
  collectFilesFromDir(..., files, ...);
}

From compaction log (in extractSSTFilesFromCompactionLog()):

sstFiles.add(sstBackupDir.resolve(f.getFileName() + ROCKSDB_SST_SUFFIX));

In both cases, dbFile is a valid Path (no null elements). Also, Path.resolve() never returns null — it returns a Path or throws NullPointerException if the argument is null.

So dbFile.toFile().getAbsolutePath() cannot be null in this flow.

[Russole]

Thanks @yandrey321 for the review.