fix(trie): delete nonexistent keys from DB

[u2]

So this PR fixed two bugs? firstly, fixed the delete operation of the nonexistent keys; secondly, fixed the delete keys in DB.

[yejiayu]

Only fixed one, delete a node that does not exist from the database when calling commit

[u2]

        for key in self.deleted_keys.drain(..) {
            self.db.remove(key.as_ref()).map_err(TrieError::DB)?;
        }

I think not just one. Maybe I misunderstood it.