Fix shrink_labels for 1D face strips in 2D distributed segmentation.

Drop test file; keep minimal change in shrink_labels only.

Co-authored-by: Cursor <cursoragent@cursor.com>

Author: sbamopoulos

cellpose/contrib/distributed_segmentation.py

@@ -884,8 +884,6 @@ def shrink_labels(plane, threshold):
     """Shrink labels in plane by some distance from their boundary"""
     squeezed = plane.squeeze()
     grads = np.gradient(squeezed)
-    # 1D face strips (2D image tiling): np.gradient returns a bare array, not a list.
-    # np.linalg.norm(1d_array, axis=0) is a scalar and would zero every pixel.
     if not isinstance(grads, tuple):
         grads = (grads,)
     gradmag = np.linalg.norm(grads, axis=0)