selftests/bpf: Avoid pinning bpf prog in the netns_load_bpf() callers

This patch removes the need to pin prog in the remaining tests in
tc_redirect.c by directly using the bpf_tc_hook_create() and
bpf_tc_attach().  The clsact qdisc will go away together with
the test netns, so no need to do bpf_tc_hook_destroy().

Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Stanislav Fomichev <sdf@google.com>
Link: https://lore.kernel.org/bpf/20221129070900.3142427-5-martin.lau@linux.dev