fix(trie): retain updates only for sparse branch nodes in the prefix set

[shekhirin]

If an extension node had a blinded child that we revealed and it turned out to be a branch node, this node will get included in the trie updates on a call to rlp_node even though its path wasn't in the prefix set

reth/crates/trie/sparse/src/trie.rs

Lines 839 to 850 in da5ffc2

	// Check if the extension node child is a hash that needs to be revealed
	if self.nodes.get(&current).unwrap().is_hash() {
	if let Some(node) = self.provider.blinded_node(current.clone())? {
	let decoded = TrieNode::decode(&mut &node[..])?;
	trace!(target: "trie::sparse", ?current, ?decoded, "Revealing extension node child");
	// We'll never have to update the revealed child node, only
	// remove or do nothing, so
	// we can safely ignore the hash mask here and
	// pass `None`.
	self.reveal_node(current.clone(), decoded, None)?;
	}
	}

This PR checks that the branch node is in the prefix set before calculating the trie updates.

[rkrasiuk]

lgtm albeit one comment

[rkrasiuk]

prefix_set_contains might be called twice (see above). let's assign to var

[shekhirin]

the value is already memoized, so we actually should call prefix_set_contains twice to avoid doingprefix_set.contains twice