Fix three_hop_blinded_path_success with different randomization

In `three_hop_blinded_path_success`, the nodes in the test ended up
at radically different block heights after channel opening. At that
point, if the CLTV randomization is done slightly different the
test payment may fail, which we fix here by ensuring all nodes are
at the same height before we go to send a payment.

Author: TheBlueMatt

lightning/src/ln/blinded_payment_tests.rs

@@ -509,6 +509,12 @@ fn three_hop_blinded_path_success() {
 	let chan_upd_2_3 = create_announced_chan_between_nodes_with_value(&nodes, 2, 3, 1_000_000, 0).0.contents;
 	let chan_upd_3_4 = create_announced_chan_between_nodes_with_value(&nodes, 3, 4, 1_000_000, 0).0.contents;
 
+	// Get all our nodes onto the same height so payments don't fail for CLTV violations.
+	connect_blocks(&nodes[0], nodes[4].best_block_info().1 - nodes[0].best_block_info().1);
+	connect_blocks(&nodes[1], nodes[4].best_block_info().1 - nodes[1].best_block_info().1);
+	connect_blocks(&nodes[2], nodes[4].best_block_info().1 - nodes[2].best_block_info().1);
+	assert_eq!(nodes[4].best_block_info().1, nodes[3].best_block_info().1);
+
 	let amt_msat = 5000;
 	let (payment_preimage, payment_hash, payment_secret) = get_payment_preimage_hash(&nodes[4], Some(amt_msat), None);
 	let route_params = get_blinded_route_parameters(amt_msat, payment_secret,