selftests/net: Drop timeout argument from test_client_verify()

It's always TEST_TIMEOUT_SEC, with an unjustified exception in rst test,
that is more paranoia-long timeout rather than based on requirements.

Signed-off-by: Dmitry Safonov <0x7f454c46@gmail.com>
Link: https://patch.msgid.link/20250319-tcp-ao-selftests-polling-v2-7-da48040153d1@gmail.com


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