Don't start with any member in autocompl. models

Fix the AutoCompletedMembers filter model to ensure that it doesn't
pick all the items from the corresponding room member model on startup,
wait until the user actually uses the completion feature to fill it.

src/backend/models/filters.py

@@ -123,11 +123,17 @@ class FieldStringFilter(ModelFilter):
     all lowercase, sensitive otherwise.
     """
 
-    def __init__(self, sync_id: SyncId, fields: Collection[str]) -> None:
-        self.fields:  Collection[str] = fields
-        self._filter: str             = ""
+    def __init__(
+        self,
+        sync_id:                    SyncId,
+        fields:                     Collection[str],
+        no_filter_accept_all_items: bool = True,
+    ) -> None:
+
+        self.fields                     = fields
+        self.no_filter_accept_all_items = no_filter_accept_all_items
+        self._filter: str               = ""
 
-        self.no_filter_accept_all_items: bool = True
 
         super().__init__(sync_id)
 

src/backend/models/special_models.py

@@ -125,8 +125,11 @@ class AutoCompletedMembers(FieldStringFilter):
         self.room_id = room_id
         sync_id      = (user_id, room_id, "autocompleted_members")
 
-        super().__init__(sync_id=sync_id, fields=("display_name", "id"))
-        self.no_filter_accept_all_items = False
+        super().__init__(
+            sync_id                    = sync_id,
+            fields                     = ("display_name", "id"),
+            no_filter_accept_all_items = False,
+        )
 
 
     def accept_source(self, source: Model) -> bool: