check: --find-lost-archives reuses the archive metadata ids found by --verify-data, fixes #8478

[mr-raj12]

Description

borg check --verify-data --find-lost-archives read every object twice: once in verify_data and once in rebuild_archives_directory to find the archive metadata objects.

verify_data now records the ids of the archive metadata objects it parses, including chunks that succeed on the --repair retry, in ArchiveChecker.archive_meta_ids. If the pass is interrupted, the ids stay None.

If archive_meta_ids is not None, rebuild_archives_directory reads only those objects. Otherwise it reads the meta dict (ro_type, without the data) of every object to find them.

Behavior change: with --verify-data and without --repair, an archive metadata object that fails in verify_data (corrupted, or a transient read error) is reported only by verify_data and not read again. The full scan no longer runs, so the extra "Skipping corrupted chunk" message is gone. error_found is the same.

Tests:

• test_check_undelete_archives and test_spoofed_archive run with and without --verify-data.
• New tests cover id collection (including a soft-deleted archive), an interrupted verify_data, and chunks kept by the --repair retry.
• test_check_find_lost_archives_corrupt_archive_meta checks which step reports a corrupt archive metadata object, with and without --verify-data.
• rebuild_archives_directory tests cover an interrupted rebuild on both paths and skipping a corrupt, non-archive or invalid msgpack object from archive_meta_ids.

fixes #8478

Checklist

• PR is against master (or maintenance branch if only applicable there)
• New code has tests and docs where appropriate
• Tests pass (run tox or the relevant test subset)
• Commit messages are clean and reference related issues

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 88.86%. Comparing base (8274470) to head (a4c459b).
⚠️ Report is 3 commits behind head on master.
✅ All tests successful. No failed tests found.

Additional details and impacted files

@@            Coverage Diff             @@
##           master   #10447      +/-   ##
==========================================
+ Coverage   88.73%   88.86%   +0.12%     
==========================================
  Files         103      103              
  Lines       19387    19405      +18     
  Branches     3023     3028       +5     
==========================================
+ Hits        17204    17244      +40     
+ Misses       1514     1495      -19     
+ Partials      669      666       -3     

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[mr-raj12]

Best merged after the stack (#10443 → #10445 → #10455 → #10464). This and #10458 change the same import line in check_cmd_test.py, so whichever goes in second needs a one-line fixup — I will push it as soon as the first one lands.