Rework volume compaction (a.k.a vacuuming) logic to cleanly support new parameters. (#8337)

We'll leverage on this to support a "ignore broken needles" option, necessary
to properly recover damaged volumes, as described in
https://github.com/seaweedfs/seaweedfs/issues/7442#issuecomment-3897784283 .

weed/command/backup.go

@@ -137,7 +137,7 @@ func backupFromLocation(volumeServer pb.ServerAddress, grpcDialOption grpc.DialO
 
 	// Handle compaction if needed
 	if v.SuperBlock.CompactionRevision < uint16(stats.CompactRevision) {
-		if err = v.Compact2(0, 0, nil); err != nil {
+		if err = v.CompactByIndex(nil); err != nil {
 			v.Close()
 			return fmt.Errorf("compacting volume: %w", err), false
 		}