RoomListStore: Unread filter should only filter rooms having unread counts (#29555)

* Use `hasUnreadCount` instead of `isUnread`

* Fix broken test

* Write test

src/stores/room-list-v3/skip-list/filters/UnreadFilter.ts

@@ -11,7 +11,7 @@ import { RoomNotificationStateStore } from "../../../notifications/RoomNotificat
 
 export class UnreadFilter implements Filter {
     public matches(room: Room): boolean {
-        return RoomNotificationStateStore.instance.getRoomState(room).isUnread;
+        return RoomNotificationStateStore.instance.getRoomState(room).hasUnreadCount;
     }
 
     public get key(): FilterKey.UnreadFilter {