pdpv0: cleanup functions may delete too much data

[Kubuxu]

ezpdpz2 after upgrading to pdpv0 and running for some time, has tarted to fail proofs due to missing pieces:

{
  "caller": "pdp/task_prove.go:201",
  "client_id": "ezpdpz-calib2",
  "dataSetId": 89,
  "dt": "2025-11-25T09:49:06.210Z",
  "error": "failed to generate proofs: failed to prove piece 0 (89, 2, 2351445): no subpiece found",
  "errorVerbose": "failed to generate proofs:\n    github.com/filecoin-project/curio/tasks/pdp.(*ProveTask).Do\n        /home/tippyflits/curio/tasks/pdp/task_prove.go:257\n  - failed to prove piece 0 (89, 2, 2351445):\n    github.com/filecoin-project/curio/tasks/pdp.(*ProveTask).GenerateProofs\n        /home/tippyflits/curio/tasks/pdp/task_prove.go:414\n  - no subpiece found:\n    github.com/filecoin-project/curio/tasks/pdp.(*ProveTask).provePiece\n        /home/tippyflits/curio/tasks/pdp/task_prove.go:537",
  "level": "error",
  "logger": "pdp",
  "msg": "Proof submission failed",
  "platform": "Curio PDP"
}

[Kubuxu]

The root cause remains unknown. The first-line solution is to disable low-level data deletion in the pdpv0 branch and track whether we end up using pieces marked as deleted.

[Kubuxu]

More debuggin from my side, it seems like the pieces might still be stored, but we seem to be deleting the them from pdp_data_set_pieces, which might carry the data deletion as well.

[Kubuxu]

So the result is that some piece entries are deleted too eagerly.