selftests/net: packetdrill: import tcp/user_timeout, tcp/validate,...

selftests/net: packetdrill: import tcp/user_timeout, tcp/validate, tcp/sendfile, tcp/limited-transmit, tcp/syscall_bad_arg

Use the standard import and testing method, as described in the
import of tcp/ecn and tcp/close , tcp/sack , tcp/tcp_info.

Signed-off-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: Soham Chakradeo <sohamch@google.com>
Link: https://patch.msgid.link/20241217185203.297935-5-sohamch.kernel@gmail.com


Signed-off-by: Jakub Kicinski <kuba@kernel.org>