Remove redundant types from comments. (#14412)

Remove type hints from comments which have been added
as Python type hints. This helps avoid drift between comments
and reality, as well as removing redundant information.

Also adds some missing type hints which were simple to fill in.

synapse/storage/databases/main/user_directory.py

@@ -185,9 +185,8 @@ class UserDirectoryBackgroundUpdateStore(StateDeltasStore):
         - who should be in the user_directory.
 
         Args:
-            progress (dict)
-            batch_size (int): Maximum number of state events to process
-                per cycle.
+            progress
+            batch_size: Maximum number of state events to process per cycle.
 
         Returns:
             number of events processed.
@@ -708,10 +707,10 @@ class UserDirectoryStore(UserDirectoryBackgroundUpdateStore):
         Returns the rooms that a user is in.
 
         Args:
-            user_id(str): Must be a local user
+            user_id: Must be a local user
 
         Returns:
-            list: user_id
+            List of room IDs
         """
         rows = await self.db_pool.simple_select_onecol(
             table="users_who_share_private_rooms",