[Process] JDT/Core FAQ page is woefully out of date when it comes to setting up a development workspace

https://github.com/eclipse-jdt/eclipse.jdt.core/wiki/FAQ-JDT-Core-Committer - has not kept pace with changes in setup.

Someone needs to follow these steps one by one and see what is invalid and fix them.

I spotted at least a few problems:

1. We seem to need a mockcompiler project that is not called out
2. We seem to need org.eclipse.test project that is not called out
3. releng repo has moved and that does not reflect in the FAQ
4. Some projects listed are not in the repos anymore.

etc