In the `NodeSupportsPreconfiguredRuntimeClassHandler`, update the check
for the runtime handler to return a failure if the
`/etc/containerd/config.toml` or `/etc/crio/crio.conf` config files do
not exist. If an error is returned, then the underlying test will be
skipped.
Test manually with starting a kind cluster and moving the containerd
config file and verifying that the test is skipped:
```
$ docker exec -it kind-worker /bin/bash
root@kind-worker:/# mv /etc/containerd/config.toml /etc/containerd/config.toml.bak
```
```
make WHAT="test/e2e/e2e.test"
$ ./_output/bin/e2e.test -kubeconfig /tmp/kubeconfig_kind -ginkgo.focus=".*should run a Pod requesting a RuntimeClass with a configured handler.*" --num-nodes=1 2>&1 -ginkgo.v=1 | tee -i "/tmp/build-log.txt"
[sig-node] RuntimeClass [It] should run a Pod requesting a RuntimeClass with a configured handler [NodeFeature:RuntimeHandler]
test/e2e/common/node/runtimeclass.go:85
[SKIPPED] Skipping test as node does not have E2E runtime class handler preconfigured in container runtime config: command terminated with exit code 1
```
Signed-off-by: David Porter <david@porter.me>
83652673b6