refactor: remove debug print statements (#12598)

### What problem does this PR solve?

This PR eliminates unnecessary debug print statements that were left in
hot paths of the codebase.

### Type of change

- [x] Refactoring

rag/flow/hierarchical_merger/hierarchical_merger.py

@@ -143,8 +143,6 @@ class HierarchicalMerger(ProcessBase):
                 if depth == self._param.hierarchy:
                     all_pathes.append(_path)
 
-        for i in range(len(lines)):
-            print(i, lines[i])
         dfs(root, [], 0)
 
         if root["texts"]: