Move review CI jobs to separate sh files

Ghost User
2020-01-30T13:33:19+01:00

### Description
This MR refactors the large complex CI jobs that create and remove the review hosts into Bash scripts.

This has multiple advantages:
- No more complex Bash in Yaml (e.g. a heredoc in a multiline Yaml item).
- Only executing tasks when needed instead of of using `x | true`.
- Smaller, more readable CI config.