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_multi-hop-error-propagation_test.go

@@ -365,12 +365,4 @@ func testHtlcErrorPropagation(ht *lntest.HarnessTest) {
 	ht.AssertHtlcEventTypes(
 		bobEvents, routerrpc.HtlcEvent_UNKNOWN, lntest.HtlcEventFinal,
 	)
-
-	// Finally, immediately close the channel. This function will also
-	// block until the channel is closed and will additionally assert the
-	// relevant channel closing post conditions.
-	ht.CloseChannel(alice, chanPointAlice)
-
-	// Force close Bob's final channel.
-	ht.ForceCloseChannel(bob, chanPointBob)
 }