Context

The EVG docs https://docs.devprod.prod.corp.mongodb.com/evergreen/Project-Configuration/Best-Practices#subprocessexec give several reasons why it should be preferred to call out to scripts instead of putting the steps in the config file.

We should additionally structure the scripts so they can be called locally and on spawn hosts. See https://docs.google.com/document/d/1d20ZRYsDn6-8IvPUMXcDLbp1fXk_ktW11fpxzN4SIvA/edit?tab=t.0 for discussion.

Definition of done

Scripts are restructured and can be run locally and on a spawn host.

Pitfalls

The EVG directory could get a bit cluttered, we might want to introduce sub folders.