selftest: packetdrill: Add tcp_fastopen_server_reset-after-disconnect.pkt.

selftest: packetdrill: Add tcp_fastopen_server_reset-after-disconnect.pkt.

The test reproduces the scenario explained in the previous patch.

Without the patch, the test triggers the warning and cannot see the last
retransmitted packet.

  # ./ksft_runner.sh tcp_fastopen_server_reset-after-disconnect.pkt
  TAP version 13
  1..2
  [   29.229250] ------------[ cut here ]------------
  [   29.231414] WARNING: CPU: 26 PID: 0 at net/ipv4/tcp_timer.c:542 tcp_retransmit_timer+0x32/0x9f0
  ...
  tcp_fastopen_server_reset-after-disconnect.pkt:26: error handling packet: Timed out waiting for packet
  not ok 1 ipv4
  tcp_fastopen_server_reset-after-disconnect.pkt:26: error handling packet: Timed out waiting for packet
  not ok 2 ipv6
  # Totals: pass:0 fail:2 xfail:0 xpass:0 skip:0 error:0

Signed-off-by: Kuniyuki Iwashima <kuniyu@google.com>
Link: https://patch.msgid.link/20250915175800.118793-3-kuniyu@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>