P1 (5/n): six GPU validation tests use the level-list constructor

test_refinement_gpu (incl. PeriodicPatchStepper alias calls),
test_channel_root_gpu, test_fine_surface_gpu, test_shifted_remap_gpu,
test_runtime_child_remap_gpu and test_refinement_three_level_multipatch_gpu
pass refinements/level_* lists; scalar and set children map to the second
refinement entry exactly as _legacy_levels did. Assertions unchanged.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

tests/validation/multigrid/test_shifted_remap_gpu.py

@@ -22,9 +22,8 @@ B=((20,16,36,40),)
 
 
 def make(ctx):
-    return FixedPatchStepper(CFG,PARENTS,context=ctx,base_block=(4,4),
-                             fine_block=(4,4),child_block=(4,4),
-                             child_rectangles_in_parent=A)
+    return FixedPatchStepper(CFG,context=ctx,refinements=[PARENTS,A],
+                             level_blocks=[(4,4)]*3)
 
 
 def initial(run):