Install cloudbees-folder into jenkins

Author: sanderv32

src/test/docker/jenkins-dockerfile/Dockerfile

@@ -1,7 +1,7 @@
 FROM jenkinsci/jenkins:latest
 
 # Load the required dependencies for the plugin under test
-RUN /usr/local/bin/install-plugins.sh git workflow-aggregator pipeline-model-extensions
+RUN /usr/local/bin/install-plugins.sh git workflow-aggregator pipeline-model-extensions cloudbees-folder
 
 # Copy the newly built plugin in the container so that it gets loaded at startup
 ADD gogs-webhook.hpi /usr/share/jenkins/ref/plugins/gogs-webhook.hpi