htlcswitch: fix TestUpdateForwardingPolicy

In this commit, we fix the TestUpdateForwardingPolicy test case after
the recent modification in the way we handling validating constraints
within the link. After the recent set of changes, Bob will properly use
his outgoing link to validate the set of fee related constraints rather
than the incoming link. As a result, we need to modify the second
channel link, not the first for the test to still be applicable.

htlcswitch/link_test.go

@@ -826,7 +826,7 @@ func TestUpdateForwardingPolicy(t *testing.T) {
 	// update logic
 	newPolicy := n.globalPolicy
 	newPolicy.BaseFee = lnwire.NewMSatFromSatoshis(1000)
-	n.firstBobChannelLink.UpdateForwardingPolicy(newPolicy)
+	n.secondBobChannelLink.UpdateForwardingPolicy(newPolicy)
 
 	// Next, we'll send the payment again, using the exact same per-hop
 	// payload for each node. This payment should fail as it won't factor