Deleted post cleanup: check is_deleted

This shouldn't make much difference in practice since deleted_time
should be updated automatically, but it's probably safest to make sure
that the posts are still deleted before cleaning them up, in case the
deleted_time ends up staying set somehow.

tildes/scripts/clean_private_data.py

@@ -87,6 +87,7 @@ class DataCleaner:
         updated = (
             self.db_session.query(Comment)
             .filter(
+                Comment.is_deleted == True,  # noqa
                 Comment.deleted_time <= self.retention_cutoff,  # type: ignore
                 Comment.user_id != 0,
             )
@@ -113,6 +114,7 @@ class DataCleaner:
         updated = (
             self.db_session.query(Topic)
             .filter(
+                Topic.is_deleted == True,  # noqa
                 Topic.deleted_time <= self.retention_cutoff,  # type: ignore
                 Topic.user_id != 0,
             )