Farmer piece cache percentage is based on remaining pieces, which is confusing after a restart #3614
Description
When I start my farmer with multiple farms totalling 10s of terabytes, it checks the previous piece cache, then starts downloading pieces.
Before I restarted it, it logged around 5% complete:
2025-07-02T00:58:40.328135Z INFO subspace_networking::node_runner: dsn: actively using 1/75 known peers
2025-07-02T00:58:53.420955Z INFO subspace_farmer::farmer_cache: Piece cache sync 5.09% complete
But after I restart, I see it return to close to zero:
2025-07-02T06:38:05.317096Z INFO subspace_farmer::farmer_cache: Piece cache sync 0.00% complete
2025-07-02T06:38:05.593328Z INFO subspace_farmer::farmer_cache: Piece cache sync 0.08% complete
2025-07-02T06:39:15.750174Z INFO subspace_networking::node_runner: dsn: actively using 1/74 known peers
...
2025-07-02T06:43:45.821057Z INFO subspace_networking::node_runner: dsn: actively using 6/74 known peers
2025-07-02T06:44:08.850549Z INFO subspace_farmer::farmer_cache: Piece cache sync 0.16% complete
2025-07-02T06:44:15.826408Z INFO subspace_networking::node_runner: dsn: actively using 7/74 known peers
2025-07-02T06:44:45.833070Z INFO subspace_networking::node_runner: dsn: actively using 25/74 known peers
2025-07-02T06:45:15.839039Z INFO subspace_networking::node_runner: dsn: actively using 5/74 known peers
2025-07-02T06:45:21.214139Z INFO subspace_farmer::farmer_cache: Piece cache sync 0.25% complete
...
2025-07-02T07:01:56.966927Z INFO subspace_farmer::farmer_cache: Piece cache sync 0.33% complete
...
2025-07-02T08:00:48.108130Z INFO subspace_farmer::farmer_cache: Piece cache sync 0.41% complete
...
2025-07-02T09:15:43.067294Z INFO subspace_farmer::farmer_cache: Piece cache sync 0.49% complete
...
2025-07-02T10:33:23.546940Z INFO subspace_farmer::farmer_cache: Piece cache sync 0.57% complete
...
2025-07-02T19:59:57.485356Z INFO subspace_networking::node_runner: dsn: actively using 19/73 known peers
A reset to zero would make sense if the percentage was based on the remaining pieces. But that's obviously not the case, because it reaches 0.16% almost immediately.
Perhaps it is based on the remaining unplotted pieces? If that's the case, then we could re-word the logs to make that clearer.