docs(api): update docs about gevent setup in app.py (#27611)

Add a warning about top level importing in gunicorn.conf.py

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

api/app.py

@@ -13,23 +13,12 @@ if is_db_command():
 
     app = create_migrations_app()
 else:
-    # It seems that JetBrains Python debugger does not work well with gevent,
-    # so we need to disable gevent in debug mode.
-    # If you are using debugpy and set GEVENT_SUPPORT=True, you can debug with gevent.
-    # if (flask_debug := os.environ.get("FLASK_DEBUG", "0")) and flask_debug.lower() in {"false", "0", "no"}:
-    # from gevent import monkey
+    # Gunicorn and Celery handle monkey patching automatically in production by
+    # specifying the `gevent` worker class. Manual monkey patching is not required here.
     #
-    # # gevent
-    # monkey.patch_all()
+    # See `api/docker/entrypoint.sh` (lines 33 and 47) for details.
     #
-    # from grpc.experimental import gevent as grpc_gevent  # type: ignore
-    #
-    # # grpc gevent
-    # grpc_gevent.init_gevent()
-
-    # import psycogreen.gevent  # type: ignore
-    #
-    # psycogreen.gevent.patch_psycopg()
+    # For third-party library patching, refer to `gunicorn.conf.py` and `celery_entrypoint.py`.
 
     from app_factory import create_app