DEV: Restore UploadRecovery specs (PR #10543)

Originally disabled in 0c0192e7dabf6959c4248fa0454da206ac9c780f. Upload specs now use separate paths for each spec worker.

Fixes an issue in UploadRecovery#recover_from_local – it didn’t take into account the testing infix (e.g. test_0) in the uploads/tombstone paths.

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