refactor: Use EMPTY_MEMBERSHIP module constant directly

Drop the redundant EMPTY_MEMBERSHIP class attribute and reference the
big_segments_common module constant directly instead of via self.

Author: jsonbailey

ldclient/impl/async_big_segments.py

@@ -19,8 +19,6 @@
 
 
 class AsyncBigSegmentStoreManager:
-    EMPTY_MEMBERSHIP = EMPTY_MEMBERSHIP
-
     """
     Internal component that decorates the Big Segment store with caching behavior, and also polls the
     store to track its status. The constructor starts the polling task.
@@ -59,7 +57,7 @@ async def get_user_membership(self, user_key: str) -> Tuple[Optional[dict], str]
             try:
                 membership = await self.__store.get_membership(user_hash)  # type: ignore[misc]
                 if membership is None:
-                    membership = self.EMPTY_MEMBERSHIP
+                    membership = EMPTY_MEMBERSHIP
                 self.__cache[user_key] = membership
             except Exception as e:
                 log.exception("Big Segment store membership query returned error: %s" % e)

ldclient/impl/big_segments.py

@@ -19,8 +19,6 @@
 
 
 class BigSegmentStoreManager:
-    EMPTY_MEMBERSHIP = EMPTY_MEMBERSHIP
-
     """
     Internal component that decorates the Big Segment store with caching behavior, and also polls the
     store to track its status.
@@ -58,7 +56,7 @@ def get_user_membership(self, user_key: str) -> Tuple[Optional[dict], str]:
             try:
                 membership = self.__store.get_membership(user_hash)
                 if membership is None:
-                    membership = self.EMPTY_MEMBERSHIP
+                    membership = EMPTY_MEMBERSHIP
                 self.__cache[user_key] = membership
             except Exception as e:
                 log.exception("Big Segment store membership query returned error: %s" % e)