Remove Delist and List Recommender Functionality

- Deleted the `delist_recommender.py` and `list_recommender.py` files from the backend API, effectively removing the associated functionality from the codebase.
- Updated the `__init__.py` file to exclude imports related to the delist and list recommenders, streamlining the API structure.
- This change is part of an ongoing effort to simplify the codebase and focus on core functionalities, enhancing maintainability and clarity.

Author: goldhaxx

backend/api/__init__.py

@@ -11,6 +11,4 @@
     snapshot,
     ucache,
     vaults,
-    delist_recommender,
-    list_recommender,
 )