chore(module-loading): remove outdated TODO and clarify import_string docstring (#56713)

* feat(module-loading): add nested attribute support to import_string

* chore: update docstrings

* chore(module-loading): remove outdated TODO and clarify import_string docstring

* chore: remove unrequired file

* chore(module-loading): remove unrequired logic

---------

Co-authored-by: Programmer-RD-AI <[email protected]>

Author: prdai

task-sdk/src/airflow/sdk/module_loading.py

@@ -25,9 +25,10 @@ def import_string(dotted_path: str):
     """
     Import a dotted module path and return the attribute/class designated by the last name in the path.
 
+    Note: Only supports top-level attributes or classes.
+
     Raise ImportError if the import failed.
     """
-    # TODO: Add support for nested classes. Currently, it only works for top-level classes.
     try:
         module_path, class_name = dotted_path.rsplit(".", 1)
     except ValueError: