This is pre-requisite work towards the unified cli.
(Other package loaders have been migrated the same way, i won't open similar diffs as this though, it's time consuming for everyone for little benefit)
Note:
This implies a scheduler's task_type migration on their backend name (P567)
Related to T2134
you can simplify this example, to only keep what matters to the test. It makes the test more readable. (Right now, I don't see what part of this file is the syntax error)