Use more pylibcudf Python enums in cudf._lib (#17288)

Similar to #17287. Also remove a `plc` naming shadowing

Authors:
  - Matthew Roeschke (https://github.com/mroeschke)

Approvers:
  - Matthew Murray (https://github.com/Matt711)

URL: #17288

python/cudf/cudf/_lib/groupby.pyx

@@ -18,7 +18,6 @@ from cudf._lib.utils cimport columns_from_pylibcudf_table
 
 from cudf._lib.scalar import as_device_scalar
 
-from pylibcudf.libcudf.replace cimport replace_policy
 from pylibcudf.libcudf.scalar.scalar cimport scalar
 
 import pylibcudf
@@ -244,13 +243,11 @@ cdef class GroupBy:
         return columns_from_pylibcudf_table(shifts), columns_from_pylibcudf_table(keys)
 
     def replace_nulls(self, list values, object method):
-        # TODO: This is using an enum (replace_policy) that has not been exposed in
-        # pylibcudf yet. We'll want to fix that import once it is in pylibcudf.
         _, replaced = self._groupby.replace_nulls(
             pylibcudf.table.Table([c.to_pylibcudf(mode="read") for c in values]),
             [
-                replace_policy.PRECEDING
-                if method == 'ffill' else replace_policy.FOLLOWING
+                pylibcudf.replace.ReplacePolicy.PRECEDING
+                if method == 'ffill' else pylibcudf.replace.ReplacePolicy.FOLLOWING
             ] * len(values),
         )
 

python/cudf/cudf/_lib/json.pyx

@@ -104,7 +104,7 @@ cpdef read_json(object filepaths_or_buffers,
         )
         df = cudf.DataFrame._from_data(
             *_data_from_columns(
-                columns=[Column.from_pylibcudf(plc) for plc in res_cols],
+                columns=[Column.from_pylibcudf(col) for col in res_cols],
                 column_names=res_col_names,
                 index_names=None
                )

python/cudf/cudf/_lib/lists.pyx

@@ -4,7 +4,7 @@ from cudf.core.buffer import acquire_spill_lock
 
 from libcpp cimport bool
 
-from pylibcudf.libcudf.types cimport null_order, size_type
+from pylibcudf.libcudf.types cimport size_type
 
 from cudf._lib.column cimport Column
 from cudf._lib.utils cimport columns_from_pylibcudf_table
@@ -49,7 +49,11 @@ def sort_lists(Column col, bool ascending, str na_position):
         plc.lists.sort_lists(
             col.to_pylibcudf(mode="read"),
             ascending,
-            null_order.BEFORE if na_position == "first" else null_order.AFTER,
+            (
+                plc.types.NullOrder.BEFORE
+                if na_position == "first"
+                else plc.types.NullOrder.AFTER
+            ),
             False,
         )
     )