selftests/bpf: Use sockaddr_storage directly in cls_redirect test

selftests/bpf: Use sockaddr_storage directly in cls_redirect test

The cls_redirect test uses a custom addr_port/tuple wrapper to represent
IPv4/IPv6 addresses and ports. This custom wrapper requires extra
conversion logic and specific helpers such as fill_addr_port(), which
are no longer necessary when using standard socket address structures.

This commit replaces addr_port/tuple with the standard sockaddr_storage
so test handles address families and ports using native socket types.
It removes the custom helper, eliminates redundant casts, and simplifies
the setup helpers without functional changes. set_up_conn() and
build_input() now take src/dst sockaddr_storage directly.

Reviewed-by: Amery Hung <ameryhung@gmail.com>
Signed-off-by: Hoyeon Lee <hoyeon.lee@suse.com>
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
Link: https://patch.msgid.link/20251121081332.2309838-2-hoyeon.lee@suse.com