Reboot - Fix conditionals in Windows provider

https://github.com/puppetlabs/puppetlabs-reboot/commit/05b7ce404b0b3fd5b2cfd4b88e864f1445626d2a was initially made to remove the control flow and in favor of the boolean &&.

This commit was reverted due to breakages as described in https://github.com/puppetlabs/puppetlabs-reboot/commit/2ad6ebb1f120243b8f075afe2444cee9c50d047a

However, this code seems wrong - and should be fixed.