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_channel_policy_test.go

@@ -420,11 +420,6 @@ func testUpdateChannelPolicy(ht *lntest.HarnessTest) {
 	ht.AssertChannelPolicy(
 		carol, alice.PubKeyStr, expectedPolicy, chanPoint3,
 	)
-
-	// Close all channels.
-	ht.CloseChannel(alice, chanPoint)
-	ht.CloseChannel(bob, chanPoint2)
-	ht.CloseChannel(alice, chanPoint3)
 }
 
 // testSendUpdateDisableChannel ensures that a channel update with the disable
@@ -773,10 +768,6 @@ func testUpdateChannelPolicyForPrivateChannel(ht *lntest.HarnessTest) {
 	// Alice should have sent 20k satoshis + fee to Bob.
 	ht.AssertAmountPaid("Alice(local) => Bob(remote)",
 		alice, chanPointAliceBob, amtExpected, 0)
-
-	// Finally, close the channels.
-	ht.CloseChannel(alice, chanPointAliceBob)
-	ht.CloseChannel(bob, chanPointBobCarol)
 }
 
 // testUpdateChannelPolicyFeeRateAccuracy tests that updating the channel policy
@@ -845,8 +836,6 @@ func testUpdateChannelPolicyFeeRateAccuracy(ht *lntest.HarnessTest) {
 
 	// Make sure that both Alice and Bob sees the same policy after update.
 	assertNodesPolicyUpdate(ht, nodes, alice, expectedPolicy, chanPoint)
-
-	ht.CloseChannel(alice, chanPoint)
 }
 
 // assertNodesPolicyUpdate checks that a given policy update has been received