selftests/bpf: Cover verifier checks for mutating sockmap/sockhash

selftests/bpf: Cover verifier checks for mutating sockmap/sockhash

Verifier enforces that only certain program types can mutate sock{map,hash}
maps, that is update it or delete from it. Add test coverage for these
checks so we don't regress.

Signed-off-by: Jakub Sitnicki <jakub@cloudflare.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Link: https://lore.kernel.org/bpf/20240527-sockmap-verify-deletes-v1-3-944b372f2101@cloudflare.com