Another spot to fully cross version continuations plugin

The continuations plugin is fully cross versioned, as it
dependes on the non-BC compiler API.

I had to make the same change externally releasing 2.11.0:

   https://github.com/scala/jenkins-scripts/pull/99/files

This fix addresses the problem in scala/scala. Without it,
we can't resolve dependencies in development.
Merge pull request #3688 from retronym/topic/continuations-cross-version-strikes-back

Another spot to fully cross version continuations plugin