Small changes to the Windows 2016 Packer build for debuggability of
provisioning:
* improve verbosity of powershell error handling
* remove unused "tools" installation
* use ssh communicator for Packer to improve Packer build times and eliminate
deprecated winrm remote access (unavailable from current macOS)
We intend to expand the nightly E2E test to cover multiple distros and
platforms. Change the naming structure for "Linux client" to the more precise
"Ubuntu Bionic", and "Windows" to "Windows 2016" to make it easier to add new
targets without additional refactoring.
Seth Hoenig