selftests/bpf: Use connect_to_addr in connect_to_fd_opt

This patch moves "post_socket_cb" and "noconnect" into connect_to_addr(),
then connect_to_fd_opts() can be implemented by getsockname() and
connect_to_addr(). This change makes connect_to_* interfaces more unified.

Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Signed-off-by: Geliang Tang <tanggeliang@kylinos.cn>
Link: https://lore.kernel.org/r/4569c30533e14c22fae6c05070aad809720551c1.1718932493.git.tanggeliang@kylinos.cn


Signed-off-by: Alexei Starovoitov <ast@kernel.org>