t/files-exit-hang-poll: Don't brute force the port number
t/files-exit-hang-poll: Don't brute force the port number

Don't brute force the port number, use `t_bind_ephemeral_port()`,
much simpler and reliable for choosing a port number that is not
in use.

Cc: Dylan Yudaken <203ae8bb785c49229d9d2ff72bddc0c8f3aba6ea@fb.com>
Cc: Facebook Kernel Team <6a543c1938e2357c042e911ad9c052b5afc2d394@fb.com>
Cc: Pavel Begunkov <8608d41fe50396a9dbd36e830be65ba791e26c05@gmail.com>
Reviewed-by: Alviro Iskandar Setiawan <acb00eee907e465a4ea2ca150e2639c8348f1d28@gnuweeb.org>
Tested-by: Alviro Iskandar Setiawan <acb00eee907e465a4ea2ca150e2639c8348f1d28@gnuweeb.org>
Signed-off-by: Ammar Faizi <a8266392a329a5c7b5ab982a8996391d75b6438e@gnuweeb.org>
Link: 104d0d4311a7915742690999d32bbf148da46b78@intel.com
Signed-off-by: Jens Axboe <cd8c6775e60d6f67a6984377324e5290df3d5358@kernel.dk>

axboe/liburing,axboe/liburing,axboe/liburing