itest: adopt itests for the new behavior

Now outgoing dust-htlcs are canceled back before the commitment
is confirmed onchain.

Author: ziggie1984

itest/lnd_multi-hop_test.go

@@ -250,18 +250,17 @@ func runMultiHopHtlcLocalTimeout(ht *lntest.HarnessTest,
 	op := ht.OutPointFromChannelPoint(bobChanPoint)
 	closeTx := ht.AssertOutpointInMempool(op)
 
+	// Dust HTLCs are immediately canceled backwards as soon as the local
+	// commitment tx is successfully broadcasted to the local mempool.
+	ht.AssertActiveHtlcs(alice, payHash)
+
 	// Bob's anchor output should be offered to his sweep since Bob has
 	// time-sensitive HTLCs - we expect both anchors are offered.
 	ht.AssertNumPendingSweeps(bob, 2)
 
 	// Mine a block to confirm the closing transaction.
 	ht.MineBlocksAndAssertNumTxes(1, 1)
 
-	// At this point, Bob should have canceled backwards the dust HTLC
-	// that we sent earlier. This means Alice should now only have a single
-	// HTLC on her channel.
-	ht.AssertActiveHtlcs(alice, payHash)
-
 	// With the closing transaction confirmed, we should expect Bob's HTLC
 	// timeout transaction to be offered to the sweeper due to the expiry
 	// being reached. we also expect Bon and Carol's anchor sweeps.