selftests/bpf: Use connect_to_addr in cls_redirect

This patch uses public helper connect_to_addr() exported in
network_helpers.h instead of the local defined function connect_to_server()
in prog_tests/cls_redirect.c. This can avoid duplicate code.

Signed-off-by: Geliang Tang <tanggeliang@kylinos.cn>
Link: https://lore.kernel.org/r/4a03ac92d2d392f8721f398fa449a83ac75577bc.1713427236.git.tanggeliang@kylinos.cn


Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>