pid1: close fds we receive via sd_notify() and cannot make use of asynchronously

This addresses #11112 fully. It mostly was addressed by
99620f457ed0886852ba18c9093b59767299121c already, but for fds not
even passed to the fdstore, this adds the missing asynchronous close
codepath.

Fixes: #11112

src/core/manager.c

@@ -2793,7 +2793,7 @@ static int manager_dispatch_notify_fd(sd_event_source *source, int fd, uint32_t
                 }
         }
 
-        _cleanup_fdset_free_ FDSet *fds = NULL;
+        _cleanup_(fdset_free_asyncp) FDSet *fds = NULL;
 
         if (n_fds > 0) {
                 assert(fd_array);