Ensure `JenkinsRule#after()` is called even when timeout is reached

[Vlatombe]

I see from time to time some tests from kubernetes-plugin timing out. When that happens, subsequent tests fail because they try to allocate the same port. I've noticed that the timeout exception isn't handled the same way as a generic failure, in particular it doesn't run after().

[jglick]

At least merge with master to rerun CI.

[jglick]

it doesn't run after().

But that may be a good thing, since shutdown invokes user code and thus could hang, right?