[Misc] Rename the variables in NeighborSampler for better readability. (#6451)

Co-authored-by: Ubuntu <ubuntu@ip-172-31-28-63.ap-northeast-1.compute.internal>

python/dgl/graphbolt/impl/neighbor_sampler.py

@@ -113,20 +113,21 @@ class NeighborSampler(SubgraphSampler):
                 self.replace,
                 self.prob_name,
             )
-            original_column_node_ids = seeds
             if self.deduplicate:
-                seeds, compacted_node_pairs = unique_and_compact_node_pairs(
-                    subgraph.node_pairs, seeds
-                )
+                (
+                    original_row_node_ids,
+                    compacted_node_pairs,
+                ) = unique_and_compact_node_pairs(subgraph.node_pairs, seeds)
             else:
                 raise RuntimeError("Not implemented yet.")
             subgraph = SampledSubgraphImpl(
                 node_pairs=compacted_node_pairs,
-                original_column_node_ids=original_column_node_ids,
-                original_row_node_ids=seeds,
+                original_column_node_ids=seeds,
+                original_row_node_ids=original_row_node_ids,
                 original_edge_ids=subgraph.original_edge_ids,
             )
             subgraphs.insert(0, subgraph)
+            seeds = original_row_node_ids
         return seeds, subgraphs