reduce number of cached meta extractors

(cherry picked from commit 5a5d5ac)

backend/meta_extractor.py

@@ -85,7 +85,7 @@ def __init__(self, cache: Cache, num_last_days: int | None = 10, *, logger: logg
         self._rooms: set[str] | None = None
         self._daily_extractors: dict[tuple[datetime.date, datetime.datetime], DailyMetaExtractor] = {}
         self._daily_extractors_lock = threading.Lock()
-        self._max_cached_extractors = 10
+        self._max_cached_extractors = 1
 
     def iterate_daily_extractors(self) -> typing.Generator[DailyMetaExtractor, None, None]:
         for day in self.cache.get_days()[:self.num_last_days]: