itest: remove unnecessary channel close and node shutdown

Since we don't have standby nodes anymore, we don't need to close the
channels when the test finishes. Previously we would do so to make sure
the standby nodes have a clean state for the next test case, which is no
longer relevant.

itest/lnd_network_test.go

@@ -133,9 +133,7 @@ func testReconnectAfterIPChange(ht *lntest.HarnessTest) {
 	// We'll then go ahead and open a channel between Alice and Dave. This
 	// ensures that Charlie receives the node announcement from Alice as
 	// part of the announcement broadcast.
-	chanPoint := ht.OpenChannel(
-		alice, dave, lntest.OpenChannelParams{Amt: 1000000},
-	)
+	ht.OpenChannel(alice, dave, lntest.OpenChannelParams{Amt: 1000000})
 
 	// waitForNodeAnnouncement is a closure used to wait on the given graph
 	// subscription for a node announcement from a node with the given
@@ -210,9 +208,6 @@ func testReconnectAfterIPChange(ht *lntest.HarnessTest) {
 	// address to one not listed in Dave's original advertised list of
 	// addresses.
 	ht.AssertConnected(dave, charlie)
-
-	// Finally, close the channel.
-	ht.CloseChannel(alice, chanPoint)
 }
 
 // testAddPeerConfig tests that the "--addpeer" config flag successfully adds