Remove dynamic and config environments
Since Puppet 4 only directory environments are supported so this was mostly dead code.
Remove left over environment entry
a61e010 removed config environments but omitted this config entry define.
Remove Debian package special case
This was an ancient workaround where puppet didn't properly depend on puppet-common. On Debian Jessie puppet already depends on puppet-common and everything newer has made puppet-common a dummy transitional package. This means we can remove the special case and fall back to the general else case.
Fixes #25839 - Determine puppetserver version in server.pp
Currently we store some parameters in the installers answers file that relate to the puppetserver version. This is because we determine them in params.pp which means init.pp has them. The result is that when a user upgrades, their answers need to be reset. Katello has a hook to always do this, Foreman has nothing. By defaulting to undef and moving the the determination into server.pp we can avoid this whole problem.