Merge pull request #16723 from pieterlexis/dnsdist-rm-h2o

feat(dnsdist): remove h2o support

diff --cc pdns/dnsdistdist/dnsdist-configuration-yaml.cc
Simple merge

diff --cc pdns/dnsdistdist/dnsdist-lua.cc
Simple merge

diff --cc pdns/dnsdistdist/dnsdist-settings-definitions.yml
Simple merge

diff --cc pdns/dnsdistdist/docs/reference/config.rst
Simple merge

diff --cc regression-tests.dnsdist/test_Protobuf.py
Simple merge