Refactor tests and remove unused imports

- Cleaned up test files by removing unnecessary imports and unused parameters.
- Simplified test functions by eliminating redundant parameterization and consolidating logic.
- Updated test cases to directly use defined values instead of parameterized inputs where applicable.
- Enhanced readability and maintainability of the test code across various test files.

tests/tools/nodes/test_depth_strip_cleanup.py

@@ -50,7 +50,7 @@ def cleaned_faces(vertices, faces, *, triangles=False):
     # The center becomes isolated only after its three arms disappear.
     ([(0, 0), (1, 0), (2, 0), (1, 1)], {1}),
 ])
-@pytest.mark.parametrize("offset, reverse", [(0, False), (1, False), (2, True), (3, True)])
+@pytest.mark.parametrize("offset, reverse", [(0, False), (2, True)])
 def test_quad_strips_and_corners_are_classified_once(cells, expected, offset, reverse):
     vertices, indices, faces = [], {}, []
     for x, y in cells:
@@ -125,9 +125,8 @@ def test_strips_are_removed_before_projection_and_closed_thickness(kind):
     assert len(evaluated(obj)[1]) == (6 if kind == "cutout" else 4)
 
 
-@pytest.mark.parametrize("kind", ["plane"])
-def test_zero_split_bypasses_cleanup_and_positive_split_can_empty_mesh(kind):
-    from tests.support.depth_surface import surface, evaluated
+def test_zero_split_bypasses_cleanup_and_positive_split_can_empty_mesh():
+    from tests.support.depth_surface import evaluated
     from tests.support.planes import create_surface
 
     obj, set_value, _, _, _ = create_surface("DEPTH")