GCP: open port on masters to collect cadvisor metrics

roles/openshift_gcp/defaults/main.yml

@@ -98,8 +98,7 @@ openshift_gcp_firewall_rules:
           - '8053'
           - '8444'
           - "{{ openshift_gcp_master_healthcheck_port }}"
-          # openshift-cluster-version/cluster-version-operator:metrics
-          - '9090'
+          - '9100'
           - '10250'
           - '10255'
           - '24224'