Remove File reference to nginx default.conf

puppet-nginx's installation process left default.conf in the configuration directory, which caused issues with the other configuration files generated by puppet-nginx.  As a result, our internal puppet manifests made sure the default.conf was removed after installing nginx.

jfryman/puppet-nginx#285 added the identical functionality to the puppet-nginx module, which caused a puppet error due to duplicate File object definitions.  Since the puppet-nginx object performs the same action, we can safely remove the default.conf File objects from the internal puppet manifests