This adds a 5 minute timeout to the end-to-end tests. The end-to-end
tests typically run in under 2 minutes. On Circle-CI the timeout is
10 minutes, at which point, Circle CI just shoots the tests in the
head so we don't get any logs.
Allows us to make use of of make's target deps instead of re-execing
make in our build target just for custom, one-shot environment changes.
Keeps e2e bin in bin/e2e/virtual-kubelet.
