Until now we only had ProjectCache.remove(Project p) which requires a
project instance. This could be a problem when running Gerrit HA in
active/active mode and a project name has to be removed from the
project-list cache on the other node. The project may not exist at that
point in time (because it was just deleted) and trying to load a Project
instance would lead to an error which would prevent removing this
project's name from the project_list cache.
Change-Id: Ida124ea95bb2cb776adbf8bd4d2bb77c0bdbbeaa
5489ad4b31