Fix uncleanable orphans issue with volume.fsck -forcePurging (#7332)

- Modified `needle_map_memory.go` to include needles with size=0 during needle map loading
- Updated `volume_write.go` to handle size=0 needles in delete operations

weed/storage/needle_map_memory.go

@@ -36,7 +36,7 @@ func LoadCompactNeedleMap(file *os.File) (*NeedleMap, error) {
 func doLoading(file *os.File, nm *NeedleMap) (*NeedleMap, error) {
 	e := idx.WalkIndexFile(file, 0, func(key NeedleId, offset Offset, size Size) error {
 		nm.MaybeSetMaxFileKey(key)
-		if !offset.IsZero() && size.IsValid() {
+		if !offset.IsZero() && !size.IsDeleted() {
 			nm.FileCounter++
 			nm.FileByteCounter = nm.FileByteCounter + uint64(size)
 			oldOffset, oldSize := nm.m.Set(NeedleId(key), offset, size)