Update to go 1.12.4

kubeadm: cleanup unused func

add owners file to util/metrics and auto-labeling

Fix golint failures of e2e/framework/util.go - part4

update the output of install-etcd.sh, show how to export the environment of etcd

Fix some shellcheck failures of cluster/*.sh

Rename some varibles and clean up codes in scheduler_binder.go

This is a part of a series for fixing golint failures for util.go.
- fixes golint failures from line 3686 to end of file at original util.go

This fixes golint failures of the following file:
- test/e2e/framework/util.go

Fix shellcheck failures on verify-readonly-packages.sh

Add soltysh and pwittrock to sig-cli-api-reviewers

Remove unused code

Support describe priority class of pod, rs, sts...

Fix shellcheck failures in stage-upload.sh

[metrics-server addon] Restore connecting to nodes via IP addresses

Fix shellcheck in hack/lib/golang.sh

Change-Id: If821920ec8872e326b7d85437ad8d2620807799d

This preference list matches is used to pick prefered field from k8s
node object. It was introduced in metrics-server 0.3 and changed default
behaviour to use DNS instead of IP addresses. It was merged into k8s
1.12 and caused breaking change by introducing dependency on DNS
configuration.

[e2e] Remove unused function and clean up redundant code

Fix shellcheck failures of hack/test-update-storage-objects.sh

Beta upgrade for feature gate VolumeSubpathEnvExpansion

Fix shellcheck failures of hack/verify-description.sh and hack/verify-import-boss.sh

Fix shellcheck failures on test-e2e-node.sh and test-integration.sh

fix detach azure disk back off issue which has too big lock in failure retry condition

Add IPv6 support to the Container Lifecycle tests

CSI - Skips deviceMounter.MountDevice for ephemeral volumes

Request network plugin in bug report template

Remove ineffectual assignment