refs https://github.com/TryGhost/Toolbox/issues/138
- This is a continuation of a bigger refactor to use async/await syntax before migrating "startGhost" methods to only use backend boot
- Removed a little bit of dead code (like admin user creation) which should speed up test execution too!
- Refactored user variables to be declared closer to their usecases instead of being high up in a global scope - variables shoul not live that far apart from the code that uses them
refs https://github.com/TryGhost/Toolbox/issues/138
- There is no good reason to keep this extra variable around just call "stop" in couple very specific cases. Even for those cases, there's `testUtils.stopGhost` method which achieves the same without additional variable to track.
refs https://github.com/TryGhost/Toolbox/issues/138
- Having the "ghost" alias only added cognitive load when reading through the test code and didn't provide any additional value. Removed the pattern to keep things simpler and more explicit
