Deprecate `features.HaveProgramHelper`

This issue came to my attention https://github.com/cilium/cilium/issues/48016. Looking into the details, this fundamentally originates in the way we do helper function probing. In the latest kernel there are quite a few helper functions that have special casing https://elixir.bootlin.com/linux/v7.2/source/kernel/bpf/verifier.c#L10274

I think we should deprecate this functionality, and remove it in 2 releases. Encourage people to use CO-RE instead, or write more targeted probes themself.