Refactor watched_movies property to use get_watched_movies

Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>

Author: glensc

trakt/users.py

@@ -541,10 +541,7 @@ def watched_movies(self):
         collection.
         """
         if self._watched_movies is None:
-            data = yield 'users/{user}/watched/movies'.format(
-                user=slugify(self.username)
-            )
-            self._watched_movies = self._build_watched_movies(data)
+            self._watched_movies = self.get_watched_movies()
         yield self._watched_movies
 
     @property