Deduplicate benchmark downloads and propagate failures

[GuyAv46]

The September 2 nightly timed out while downloading benchmark indices. The all-benchmarks path starts 73 downloads for 38 unique URLs with verbose progress output.

Deduplicate URLs and suppress progress output while retaining unlimited parallelism so larger runners can use their available bandwidth. Set a 60-second network timeout, three attempts, and a five-second retry wait. Enable strict shell error handling so failed downloads fail the step instead of being masked by exit 0.

Validation: shell syntax and whitespace checks; mocked downloads verified default/all and HNSW/SVS selections, one request per unique URL, download options, failure propagation in both paths, and no downloads for benchmarks without data. Rechecked deduplication and failure propagation after restoring unlimited parallelism. Full benchmark execution remains for CI.

Failure: https://github.com/RedisAI/VectorSimilarity/actions/runs/33677359784/job/100405740515

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Note

Low Risk
CI/benchmark setup script only; no production or library behavior changes.

Overview
Refactors benchmark index fetching in bm_files.sh behind a shared download_indices helper used for both the all-benchmarks and single-suite paths.

URLs are merged from the index list files, blank lines dropped, and sort -u so each URL is fetched once while keeping parallel wget (-P 0). Downloads use quieter logging (--no-verbose), a 60s timeout, three tries with a 5s retry wait, and set -euo pipefail so a failed download fails the step instead of being hidden behind success exits elsewhere in the script.

^{Reviewed by Cursor Bugbot for commit 46646fc. Bugbot is set up for automated code reviews on this repo. Configure here.}

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 97.40%. Comparing base (227e305) to head (46646fc).

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1030      +/-   ##
==========================================
- Coverage   97.43%   97.40%   -0.03%     
==========================================
  Files         141      141              
  Lines        8686     8686              
==========================================
- Hits         8463     8461       -2     
- Misses        223      225       +2     

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