Update siafile Health method to ignore deleted files
During testing of the unstable RC users were seeing a number of panic statements due to the number of stuck chunks not aligning during the calculation of the siafile
health. One situation where this could happen is if the siafile
has been marked as deleted as we do not set the stuck status of a chunk if it is deleted but we were still calculating the health.
This MR updates Health
to ignore deleted files.