Fix tcp_fin_retransmission_netstack_test

Netstack does not check ACK number for FIN-ACK packets and goes into TIMEWAIT
unconditionally. Fixing the state machine will give us back the retransmission
of FIN.

PiperOrigin-RevId: 363301883

pkg/tcpip/transport/tcp/rcv.go

@@ -260,7 +260,7 @@ func (r *receiver) consumeSegment(s *segment, segSeq seqnum.Value, segLen seqnum
 		case StateEstablished:
 			r.ep.setEndpointState(StateCloseWait)
 		case StateFinWait1:
-			if s.flagIsSet(header.TCPFlagAck) {
+			if s.flagIsSet(header.TCPFlagAck) && s.ackNumber == r.ep.snd.sndNxt {
 				// FIN-ACK, transition to TIME-WAIT.
 				r.ep.setEndpointState(StateTimeWait)
 			} else {

test/packetimpact/runner/defs.bzl

@@ -289,8 +289,6 @@ ALL_TESTS = [
     ),
     PacketimpactTestInfo(
         name = "tcp_fin_retransmission",
-        # TODO(b/181625316): Fix netstack then remove the line below.
-        expect_netstack_failure = True,
     ),
 ]