Switch to distroless for base image

[Raffo]

What would you like to be added:

Switching to distroless from alpine. Follow up to https://github.com/kubernetes-sigs/external-dns/issues/3385 . I'll keep this issue open for a bit to hear concerns from the community. This could be a breaking change for several users out there so it needs to be carefully announced at the very minimum.

Why is this needed:

To reduce maintenance overhead and vulnerabilities given the current release times.