e2e: poll state of test

The new support in ginkgo for progress reports while a test runs dumps
information about where a test is stuck when it runs too long. This can provide
additional insights into what the test is waiting for.

For the Kubernetes jobs using ginkgo-e2e.sh, such dumps are now enabled after
300 seconds and then get repeated every 20 seconds. The initial delay is
intentionally the same as for warning about a slow test. The rationale is that
such test runtimes are unexpected and may need further information to diagnose
why they are slow.

With -ginkgo.source-root, Ginkgo is able to locate the Kubernetes source code
and display small source code snippets for functions that are related to the
test, determined through a heuristic that assumes that all files under the test
suite are for the tests in it.

hack/ginkgo-e2e.sh

@@ -198,6 +198,9 @@ fi
   --dns-domain="${KUBE_DNS_DOMAIN:-cluster.local}" \
   --prepull-images="${PREPULL_IMAGES:-false}" \
   --ginkgo.slow-spec-threshold="${GINKGO_SLOW_SPEC_THRESHOLD:-300s}" \
+  --ginkgo.poll-progress-after="${GINKGO_POLL_PROGRESS_AFTER:-300s}" \
+  --ginkgo.poll-progress-interval="${GINKGO_POLL_PROGRESS_INTERVAL:-20s}" \
+  --ginkgo.source-root="${KUBE_ROOT}" \
   ${MASTER_OS_DISTRIBUTION:+"--master-os-distro=${MASTER_OS_DISTRIBUTION}"} \
   ${NODE_OS_DISTRIBUTION:+"--node-os-distro=${NODE_OS_DISTRIBUTION}"} \
   ${NUM_NODES:+"--num-nodes=${NUM_NODES}"} \