netdevsim: remove udp_ports_sleep

Now that there is only one path in udp_tunnel, there is no need to
have udp_ports_sleep knob. Remove it and adjust the test.

Cc: Michael Chan <michael.chan@broadcom.com>
Reviewed-by: Aleksandr Loktionov <aleksandr.loktionov@intel.com>
Signed-off-by: Stanislav Fomichev <stfomichev@gmail.com>
Link: https://patch.msgid.link/20250616162117.287806-6-stfomichev@gmail.com


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