* [jenkins] refer to sizes in most pipeline code
* switch back to `linux && immutable` for small instances
Co-authored-by: spalger <spalger@users.noreply.github.com>
Co-authored-by: Elastic Machine <elasticmachine@users.noreply.github.com>
Co-authored-by: spalger <spalger@users.noreply.github.com>
Co-authored-by: Elastic Machine <elasticmachine@users.noreply.github.com>