(maint) Refactor Dockerfile "edge" and "release"
(maint) Refactor Dockerfile "edge" and "release"

 - From source builds and package builds have very similar final
   behavior - that is, they install a deb, then install a package /
   package command. With source builds, it's the file from the build
   stage, while release builds are from the upstream repo

   Factor this into the "final" stage of the build, setting the
   install_path argument to the command issued to apt-get install.

   Use an ADD command to download the .deb file from the appropriate
   upstream location, depending on if the build is from source or
   packages.

   NOTE: this can change caching behavior with buildkit as the "final"
   stage should always perform an apt-get install which accounts for
   approximately 35 seconds on a local machine each time.

puppetlabs/puppetserver,puppetlabs/puppet-server,puppetlabs/puppet-server,puppetlabs/puppetserver,puppetlabs/puppet-server,puppetlabs/puppetserver,puppetlabs/puppetserver