VPA: fix bash set options

The `set` in `hack/update-kubernetes-deps-in-e2e.sh` contains redundant
options:
* `errexit` equals `-e`
* `nounset` equals `-u`

Also, I have misunderstood how to correctly set options in:
kubernetes#2531

Resource:
https://www.gnu.org/software/bash/manual/html_node/The-Set-Builtin.html

vertical-pod-autoscaler/hack/update-kubernetes-deps-in-e2e.sh

@@ -19,7 +19,7 @@
 # K8S_TAG - k8s version to use for the dependencies update.
 # Suggested format is K8S_TAG=v1.10.3
 
-set -eou errexit pipefail nounset
+set -euo pipefail
 
 K8S_TAG=${K8S_TAG:-v1.16.2}
 K8S_TAG=${K8S_TAG#v}