Fix: Add missing Jenkins WAR dependency
Fix: Add missing Jenkins WAR dependency

Unfortunately tests were failing after the upgrade to JPI plugin
v0.43.0, due to [0].

To solve this, we make sure we re-add it for runtime only, using the
Jenkins version we're targeting.

[0]: https://github.com/jenkinsci/gradle-jpi-plugin/issues/190#issuecomment-950010526

jenkinsci/job-dsl-plugin,jenkinsci/job-dsl-plugin,jenkinsci/job-dsl-plugin