minor: test fixes and diagnostic rake task

I had played around with disabling GC for test runs for speed, but speed isn't everything. This was causing some failures on Jenkins and I suspect it might be some of the cause for the headaches Gary has been running into as well.

This pull request removes the GC toggles and also adds a quick diagnostic info task per Gary's request. It also includes a small addition to the cleanup task to make sure we're mopping up correctly on jenkins.