bump metrics server version to v0.3.7 and make it multi-arch

Bumping the metrics-server version to v0.3.7. In this version,
metrics-server started building multi-arch images. To properly support
non-amd64 nodes, we should bump the version and remove the -amd64 in the
image path. (https://github.com/kubernetes-sigs/metrics-server/pull/492)

```release-note
metrics-server now uses v0.3.7 and supports multi-arch Kubernetes nodes.
```

cluster/addons/metrics-server/metrics-server-deployment.yaml

@@ -23,24 +23,24 @@ data:
 apiVersion: apps/v1
 kind: Deployment
 metadata:
-  name: metrics-server-v0.3.6
+  name: metrics-server-v0.3.7
   namespace: kube-system
   labels:
     k8s-app: metrics-server
     kubernetes.io/cluster-service: "true"
     addonmanager.kubernetes.io/mode: Reconcile
-    version: v0.3.6
+    version: v0.3.7
 spec:
   selector:
     matchLabels:
       k8s-app: metrics-server
-      version: v0.3.6
+      version: v0.3.7
   template:
     metadata:
       name: metrics-server
       labels:
         k8s-app: metrics-server
-        version: v0.3.6
+        version: v0.3.7
     spec:
       securityContext:
         seccompProfile:
@@ -51,7 +51,7 @@ spec:
         kubernetes.io/os: linux
       containers:
       - name: metrics-server
-        image: k8s.gcr.io/metrics-server-amd64:v0.3.6
+        image: k8s.gcr.io/metrics-server/metrics-server:v0.3.7
         command:
         - /metrics-server
         - --metric-resolution=30s
@@ -93,7 +93,7 @@ spec:
           - --memory={{ base_metrics_server_memory }}
           - --extra-memory={{ metrics_server_memory_per_node }}Mi
           - --threshold=5
-          - --deployment=metrics-server-v0.3.6
+          - --deployment=metrics-server-v0.3.7
           - --container=metrics-server
           - --poll-period=300000
           - --estimator=exponential