5632613c5b
Automatic merge from submit-queue (batch tested with PRs 51553, 51538, 51663, 51069, 51737)
Allow enable pod priority feature gate for GCE and configure priority for kube-proxy
**What this PR does / why we need it**:
From #23225, this PR adds an option for user to enable pod priority feature gate using GCE startup scripts, and configure pod priority for kube-proxy when enabled.
The setup `priorityClassName: system` derives from: ce1485c626/staging/src/k8s.io/api/core/v1/types.go (L2536-L2542)
The plan is to configure pod priority for kube-proxy daemonset (https://github.com/kubernetes/kubernetes/pull/50705) in the same way.
**Special notes for your reviewer**:
cc @bsalamat @davidopp @thockin
**Release note**:
```release-note
When using kube-up.sh on GCE, user could set env `ENABLE_POD_PRIORITY=true` to enable pod priority feature gate.
```
Container Linux image
The Container Linux Operating System is a Linux distribution optimized for running containers securely at scale. CoreOS provides a Container Linux image for Google Cloud Platform (GCP).
This folder contains configuration and tooling to allow kube-up to create a Kubernetes cluster on Google Cloud Platform running on the official Container Linux image.