Merge pull request kubernetes#89461 from wawa0210/change-ip-masq-os-label

[Trival] beta.kubernetes.io/os deprecated since v1.14, are targeted for removal in v1.18

Author: k8s-ci-robot

cluster/addons/ip-masq-agent/ip-masq-agent.yaml

@@ -44,7 +44,7 @@ spec:
           - name: config
             mountPath: /etc/config
       nodeSelector:
-        beta.kubernetes.io/os: linux
+        kubernetes.io/os: linux
         node.kubernetes.io/masq-agent-ds-ready: "true"
       volumes:
         - name: config