Mesh file naming convention is not uniform

[smishra3]

Nuclei_localization code is failing to run for some files as there are two naming conventions:

1. DataID-prefixed: {data_id}_collagenIV_segmentation_mesh.vtm (50 files)
2. Generic: collagenIV_segmentation_mesh.vtm (129 files)

Current implementation can't handle both conventions