Currently, we don't overwrite the transport options once they have been set the first time. For example you could create a machine 'my_machine' and set the ssl_username to 'foo' and that is the username we will use for all later occurances of machine 'my_machine'.
So for now, lets not try and change that. If you initially have your machine_options setup to use SSL with thumbprint auth, then thats how it will stay.```
This is to update where we pull from for winrm, to more closely match ssh.
https://github.com/chef/chef-provisioning-aws/pull/441#discussion_r52056464