Getting rid of kumahq/coredns-builds

[slonka]

Description

When can we get rid of https://github.com/kumahq/coredns-builds/ (now that we have our own DNS)?

xrel kumahq/coredns-builds#36

[bartsmykla]

Triage: There is an option to opt out from our built-in DNS server so we have to maintain this until we're gonna rid of it, which will probably happen in 3.0. Until then, it should stay up