Clean up repository

[gnl42]

          > Let me rephrase that. Why are these "projects" around if it requires special knowledge to import the repository in order to have a clean workspace? What's the purpose of the projects? George

…

• mylyn.builds/org.eclipse.mylyn.hudson.tests/testdata the testdata is used for the setup of the Jenkins Test Instance (jobs/test-ant/config.xml)
• mylyn.reviews/tbr this is no longer active but I do not want to delete it yet so I first only do not do a Project Import for the projects
• mylyn.docs this is the previous location of https://github.com/eclipse-mylyn/org.eclipse.mylyn.docs/ and we can remove this now
• /org.eclipse.mylyn.java.tests/target I found a few other cases where a Maven build left .project files in the build (target) folder and a Project Import added those projects

Originally posted by @BeckerFrank in https://github.com/eclipse-mylyn/org.eclipse.mylyn/issues/65#issuecomment-1513240905

[gnl42]

@BeckerFrank

I think it is time to remove the vagrant setup.