Fix ETag fallback to dataStoreETag for ring-s3-rdma-http objects

[borisfaure]

When content-md5 is absent (e.g. parts written by ring-s3-rdma-http which stores ETag only as "1:" in dataStoreETag), fall back to extracting the hex portion from dataStoreETag for use as the ETag in list entries.

Issue: ARSN-579

[bert-e]

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[bert-e]

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[claude]

No tests cover _parseListEntries today, and this adds non-trivial branching (array vs single location, colon parsing). Consider adding a unit test that exercises at least: (1) content-md5 present (existing behavior), (2) content-md5 absent with partLocations array containing a dataStoreETag like "1:abc123", (3) content-md5 absent with no partLocations.

— Claude Code

[claude]

The ETag fallback logic is correct and handles edge cases well (undefined partLocations, empty array, missing colon). One concern:

- No test coverage for _parseListEntries, including the new fallback branches
- Add unit tests covering: content-md5 present, content-md5 absent with dataStoreETag fallback, and content-md5 absent with no partLocations

Review by Claude Code

[codecov]

Codecov Report

❌ Patch coverage is 60.00000% with 4 lines in your changes missing coverage. Please review.
✅ Project coverage is 73.47%. Comparing base (06da567) to head (c9953a2).

Files with missing lines	Patch %	Lines
lib/storage/metadata/MetadataWrapper.js	60.00%	4 Missing ⚠️

Additional details and impacted files

@@                 Coverage Diff                 @@
##           development/8.4    #2622      +/-   ##
===================================================
- Coverage            73.48%   73.47%   -0.01%     
===================================================
  Files                  222      222              
  Lines                18183    18193      +10     
  Branches              3787     3769      -18     
===================================================
+ Hits                 13361    13367       +6     
- Misses                4817     4821       +4     
  Partials                 5        5              

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[francoisferrand]

Falling back to datastore ETag seems very risky, as ETag may thus change: for exemple in case of transition (or other obscure features: transient locations...) to another storage location.
→ ETag should be written by Cloudserver when creating the object.