Change common projectId Config to be able to be usable at build time

[jfbenckhuijsen]

          The groupId is at runtime because it could change at runtime, not just for the metadataserver.

To have it in both, we should use something like BUILD_AND_RUNTIME_FIXED I think, I'll prefer to avoid switching to that now.

What I propose is to use a new config root, and add another projectId config in it, then open an issue so we can remove this new props.
Thanks to that, we can unlock this PR.

Originally posted by @loicmathieu in #707 (comment)