Adding selftest to verify that struct_ops maps are auto attached by
bpf skeleton's `*__attach` function.
Signed-off-by: Mykyta Yatsenko <yatsenko@meta.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20240621180324.238379-1-yatsenko@meta.com